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Internetworking Technologies
An Engineering Perspective

Rahul Banerjee
Computer Science & Information Systems Group
Birla Institute of Technology & Science
Pilani, India

Prentice-Hall of India

This small initiative is dedicated to my loving parents

Mrs
...
Ramanand Banerjee
Who have been the guiding lights of my life and to whom I owe whatever
little I have been able to achieve
...
Those inquisitive eyes, small and innocent queries about everything she notices
and finds either interesting or frightening, make the mother sometimes cuddle the child
with all her affection and at times feel a bit irritated due to the same question being
asked time and again
...
And, that’s when a small enterprise takes
its root in some corner of the teacher’s mind so that the hardship of his own students
could be somewhat reduced, if not completely eliminated
...
The book, that originated from my lecture-notes, was made available at my
website along with a lot of other supporting aids including customizable slides, FAQs
and On-line Discussion Forum etc
...
What is in your hands
right now is the print version of part of this work
...
bits-pilani
...
in/~rahul/
...

The presented material has been
extensively classroom tested and used by on as well as off-campus students of the
university
...
The organization is largely modular and therefore
would permit an instructor to choose his own set of chapters in almost any sequence he
considers suitable
...

The book has been written as a text on internetworking technologies that should
also cater to the needs of the working engineers who wish to update themselves about
various associated technologies or those who wish to have a brief survey of the state-ofthe art so as to decide the exact direction they may wish to take for their research and
development initiatives
...
It takes a simple
approach to illustrate intricate concepts as well as encourages the reader to take his first
critical step forward through end-of-the-chapter exercises
...

The book has been organized into twelve chapters and four appendices divided
into three parts
...
The second part of the book takes up the system-level
architectures
...
Finally the Appendices present a set of
research / development draft papers that have emanated from the projects discussed in
the Part-three
...

Like any work of this nature, this work may have a few errors that may have
escaped unnoticed
...

I would fail in his duty if I do not gratefully acknowledge the support,
encouragement and inspiration that I received from my friends and colleagues
...
S
...
B
...
Natarajan (Dean of DLP at
BITS), Dr
...
R
...
Subramanian, CEO: Answerpal
...
Rajeev Kumar of
IIT Kharagpur, Dr
...
Pascal Lorenz of UoHA
(France), Dr
...
(Spain), Dr
...
Robert Fink of UCB (USA), Mr
...

Latif Ladid of Ericsson (Luxembourg) for their support and encouragement in many
forms
...
Ramanand
Banerjee and Mrs
...
Prof
...
Bundle, Ms
...
Bhardwaj, Mr
...
Anand Gangele deserve special thanks for being there all the time
whenever I needed them
...
Narendra Saini and Mr
...
The PrenticeHall team of Mr
...
Vasudevan, Mr
...

Shamim were instrumental in timely execution of the project
...


BITS, Pilani
November 21, 2002

Rahul Banerjee

Contents
Preface

Part-I Internetworking, Multimedia, Compression and Intelligent
Agent Technology Basics
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The Multimedia Internetworking Technology Basics
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Summary
Recommended Readings
Exercises

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Introduction
Space / Storage Compression
Lossy versus Lossless Data Compression
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Lossless Compression
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Lossy Compression
Graphics Metafiles
Language-based Redundancy Probabilities
Primary Classes of Data Encoding Techniques
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Entropy Encoding
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Source Encoding
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Statistical Encoding / Arithmetic Compression Technique
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Repetitive Sequence Suppression based Encoding Technique
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Differential Source Encoding Techniques
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The Transform based Source Encoding Techniques
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Huffman Encoding Techniques
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Adaptive Huffman Encoding
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The Lampel-Ziv Encoding Techniques
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10 The Lampel-Ziv Welsh (LZW -78) Encoding Technique
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11 The V
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1 Dictionary Pruning
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12 Discrete Cosine Transform based Compression Scheme
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13 Wavelets based Compression Scheme
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14 Fractal Compression Scheme
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15 Digital Video Interactive (DVI) Compression Scheme
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16 Other Compression Tools
The GIF Compression
The PNG Compression
The JPEG Compression
The MPEG Compression
Summary
Recommended Readings
Exercises

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Introduction
Intelligent Software Systems
Intelligent Agents
Attributes of Intelligent Agents
Intelligent Architectures
Internetworking Applications of Intelligent Agents
Role of Agents
Components of IA based Distributed Systems
Other Aspects of Intelligent Agents
IBM Aglet Technology Architecture
The Stanford’s JAT Technology Architecture

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The JAFMAS Technology Architecture
Summary
Recommended Readings
Exercises

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Part-II Internetworking System Architectures
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Major Goals of IPv6 Design
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How to convert a 48-bit Ethernet Address into the IEEE EUI-64
Address?
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The IPv6 Base Header Design
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1 Valid Address-Lifetime
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1 Associated Factors of Autoconfiguration
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3 The Stateful Autoconfiguration
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14 Time-sensitive IPv6 MM Traffic Over the Ethernet
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15 A Quick Note on Mobile IPv6
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16 On the Current State of IPv6 Research, Development and Deployment
Around the World
On the Congestion Control in Interneworks
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Congestion Control Strategies
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‘Arbitrary Packet Rejection-based’ / ‘Reject-on-Getting-Full’
Congestion Control Scheme
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Permit-based / Token-based / Isarithmic Congestion Control
Scheme

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The Choke Packet Scheme of Congestion Control
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Deadlock due to congestion
More on the Generic Transport Layer Concepts
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Transport Layer Responsibilities
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Generic Transport Service Primitives
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Generic Transport Service Primitives
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Transport Service Primitives: The Berkeley Sockets Set for the TCP
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The Transport Service Access Point (TSAP) and the Network Service
Access Point (NSAP)
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QoS Considerations in the TL As Used During the Option Negotiation
Process
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Inside the TCP
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The 3-Way Handshake in TCP
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Client Crash Recovery Strategies
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The Internetwork Routing Architectures
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Internetwork Management Architectures

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Internet Security Architectures
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Internetwork-based Video-on-Demand Architectures
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Introduction
Types of Video-on-Demand Technologies
The Video-on-Demand System
The VoD Architecture
Basic Issues in VoD Design
Constituents of a VoD System
Internetworking Aspects of Video-on-Demand Technology
Case Study of the Cisco’s IP/TV Solution 130
Case Study of the Ichcha-Drishti: Case Study of the W
orld’s First Native IPv6capable VoD System (VoDv6)
Summary
Recommended Readings
Exercises

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6

Introduction
Classification of Digital Library Architectures
Major Digital Library Architectures
Basic Issues in Digital Library Design: Internetworking Viewpoint
Constitution of a Digital Library
Internetworking Aspects of Digital Libraries: Multimedia Object Handling
Case Study of the Stanford Digital Library Architecture

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Internet Commerce Architectures
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Introduction
Principal Objectives of Internet Commerce
Fundamental Components of Internet Commerce Frameworks
Electronic Data Interchange (EDI)
The EDI Architecture
Electronic Funds Transfer (EFT)
Secure Electronic Transactions (SET)
The SET Architecture
The X
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Internet Programming
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1 Creating threads
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2 The Java Script: A Scripting Language
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2 Java Script: A Partial Event List
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The ActiveX Scripting Services
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1 Classes of ActiveX Scripting Components
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2 The VB Script and the Visual Basic
XML: A Quick Look
12
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1 XML and Java: A Quick Look
Summary
Recommended Readings
Exercises

Appendices
A-1
A-2
A-3
A-4

Index

A Revised Version of the IETF Internet Draft on the IPv6 Quality-of-Service through the
Modified Flow-label Specification
A Revised Version of the IETF Internet Draft on the IPv6 Quality-of-Service through the
Modified Hop-by-Hop Extension Header Specification
A Quick-view Chart of Major Internetworking Research and Development Initiatives
Around the World
Bibliography

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Chapter –1

Introductory Concepts in Internetworking
Interaction Goals
Objectives of this chapter are to define internetworks, discuss their basic
constituents, learn about the advantages they offer, realize the design problems
they pose, learn various design-specific concepts and appreciate the wide spectrum
of applications they may be closely associated with
...

At the end of this chapter, you should be able to:
• Identify an internetwork as the Internet, Intranet or Extranet;
• Identify the design issues in each of these cases,
• Identify the right way to hook-up two internetworks,
• Analyze the correctness of the internetwork design approach,
• Tell about how to extend an existing design without throwing away existing
setup
...
1 Introduction
With each passing day, the people living in all parts of the world are getting closer to
one-another, thanks to the years of human quest for making this world a better place to
live! Several thousands of man-hours have made this journey towards this level of
technological advancements possible
...
An outstanding contribution that has accelerated this growth of
information technology and thereby helped people to come closer than ever, in terms of
collaborative activities at the least, is the Internet
...
Most of them wanted to join the rest of the
information world by further connecting to the Internet
...
Clearly, all of these developments
saw the internetworking technology to evolve as an important technology in its own right!
Times changed
...
This work attempts to
introduce you to this wonder world of technology in a step-wise and guided manner!

1
...

It may consist of several Local, Metropolitan or Wide Area Networks interconnected via a
LAN, MAN or a WAN oriented communication technology, depending upon the specific
context of use
...
3 Hierarchy in Internetworks
Theoretically speaking, a single level hierarchy, i
...
a flat hierarchy is possible to attain in
case of any network
...
Unlike the local area
networks, where hierarchical architecture is seldom used, it is common to find both local
as well as wide area internetworks having a two or greater levels of hierarchy
...
An
internetwork may have a flat or multilevel (Tree-like) hierarchy
...
Kamoun & L
...
4 Classification of Internetworks
There exist three classes of Internetworks for most of the practical and analytical
purposes:
• The Global Public Internetwork: The Internet
• The Wholly Owned / Private Internetworks: Intranets
• The Hybrid Internetwork-- private networks / internetworks
connected through the Internet: Extranets

1
...
In
common practice, a single organization or institution wholly owns the entire campus
internetwork including its communication subnet
...
The latter may be desirable in some cases when

the campus is very large and comprises of a vast set of buildings spread over it
...

Examples of the LAN technologies include the popular Ethernet, Fast Ethernet, Gigabit
Ethernet, Token Bus, Token Ring, FDDI and ATM LAN, whereas examples of WAN
technologies include VSAT, Radio, Global System for Mobile communication (GSM),
Cellular Digital Packet Data (CDPD), CDM, ATM WAN etc
...

This, however, is a non-issue for a campus-wide internetwork (except for the relatively
high one-time upgrading / installation cost)
...

Many designers prefer using a combination that could be a subset of Shared Hubs
(conventional / intelligent type), ATM Switches, CDDI / FDDI Concentrators, DLL
Switches, Multi-layer Switches, Transparent / Source Routing Bridges, Routers (single /
multi-protocol type) and other existing devices / media in such a manner that the design
could provide an extensible, cost-effective and acceptably efficient internetwork setup
...


1
...
These may be further categorized as:
•
•
•

LAN Switching (Layer-2 / Layer-3)
ATM LAN Switching
Traditional Routing (IPv4 and IPv6 routing included)

Major Features of Layer-2 LAN Switches include the following:
•
•
•

Layer-2 LAN Switches (Ethernet / Token Ring) operate at
the Data Link Layer
...

They offer greater bandwidth per node-pair and improved
performance cost-effectively
...

They provide switched routing functions with great degree
of configurability in terms of QoS, Traffic Control, Subnet
Security etc
...

They are, however, relatively poorly suited to real-time
traffic
...


Major Features of ATM LAN Switches are as follows:
•
•
•
•

•

ATM LAN Switches offer high-speed LAN switching and allow
a high bandwidth
...

They also offer a guaranteed QoS, guaranteed orderly arrival
of data units, easy Traffic Control, Subnet Security etc
...
The ATM
LANE technology allows MAC-sub layer compatibility with
other common LAN protocols and therefore existing LAN
applications may continue to run atop an ATM LAN as if they
are running in their native LAN environments
...


1
...
Basically, what is a LAN or a
LAI to a ‘local area’ the same is WAN or a WAI to a ‘wide area’
...
Technology classes for local and wide area networks and
internetworks overlap each other
...
8 Competing WAN Technologies
Circuit Switching Technologies:
•
•

Users can use the whole channel bandwidth assigned to them without any
fear of blockade, infringement or delay
...


•

Once allotted, the channel and its entire bandwidth is reserved for the user
until the circuit is explicitly released / terminated even when the channel is
idle or only a fraction of the bandwidth is in use
...


Packet Switching Technologies:
•
•

Users can share the available channel bandwidth amongst them without
being aware of this fact
...


Virtual Circuit Switching Technologies:
•
•
•
•

These technologies attempt to provide the best of packet switching as
well as circuit switching worlds and display some of the features of
each of these
...

As the bandwidth requirement soars, in many situations, these
technologies actually offer cheaper routing elements compared to
those of the packet switching schemes
...


1
...
1 Wide Area Technology: Other Classification Schemes
In yet another classification, we may further regroup these technologies into classes
like ATM (WAN / WAI) / Frame Relay / X
...

In a nutshell, it may be said that there may be several overlapping classification
schemes that may be applied to any set of such technologies
...

What is common to all of the WAN classification schemes is the fact that none of
them is usually classified with respect to any layer higher than the Layer-3 (i
...
the
Network Layer in the OSI model)
...
9 Steps Involved in Internetwork Design
Requirement analysis: Statistical analysis of the specific and general requirements
of an internetwork and its various segments in terms of hourly, six-hourly, twelve-

hourly, daily, weekly, monthly and yearly traffic is one of the key steps in the
internetwork design
...

Projections: Projection of near and to some extent distant future requirements of an
in-design / under-expansion internetwork is a necessary step that helps a designer to
foresee the likely growth and usage pattern of an internetwork and make suitable
provisions right at the architectural design stage
...
This step also guarantees investment protection to
an appreciable extent
...
It is a designer's responsibility to ensure that he / she does not use a
technology, which is likely to necessitate sizeable re-investment in near future
...

Technology and performance analysis: Analysis of the economics of the chosen
technology vis-à-vis the expected performance is another step that may prevent
certain seemingly attractive but inherently uneconomical design choices to be
identified even before the pilot-implementation / prototype-building stage
...
This, to a certain extent, may be
desirable too -- particularly, for the sake of adaptability and auto-configuration type of
requirements
...
It
is, therefore, designer's job to ensure that the network -- imbibes just the right degree
of sensitivity by design, not by chance
...


1
...


1
...
They make it easy to accommodate design changes
...

Hierarchical Internetworking models compared to the huge monolithic network design
models / architectures, obviate the need to make large-scale, and often expensive,
changes influencing several component sub-systems
...

1
...
1 The Hierarchical Internetworking Design Models: The Architectural View
Hierarchical Internetworking models are basically three-layer models:
Layer-1 comprises of the functional building blocks, which ensure optimal Transport
operations between the involved network locations
...

Layer-2 often called as the Distribution Layer is primarily responsible for providing
connections between the requested sites as per a structured / default policy
...
This layer is often called as the Local Access Layer for this reason
...
12 Summary
Internetworks have come of age
...
The best-known internetwork is
the public Internet -- which saw unparalleled growth (or was that an explosion?) soon
after emergence of the World Wide Web technology
...
Due to the reasons of varied degrees of privacy, security, administrative
policy, distances, data transmission needs and associated economics of scale, a few
other derivative technologies have begun evolving into their own -- most promising of
these categories are the Intranet Technologies and the Extranet Technologies
...

There exist several areas of overlap -- right from the switching technologies to the
routing protocols and congestion control strategies! Each type of internetwork needs to
address issues like stability, worst-case response time, availability, synchronization,
concurrency control and resource sharing without policy violation as well
...
However, not every
such arrangement is always by choice -- at times, it just happens (for instance, as a
result of incremental unplanned growth of networks within an environment)
...
The only advantage
some of these designs do offer is their relatively low development time
...
Often, these hierarchical design models are three layer
architectures, comprising of the Core Layer / Backbone Layer, Distribution Layer and
Local Access Layer
...
What cannot be ignored is the functionality that a layer is
supposed to offer! Whatever be your design choice and strategy, you have to provide
the minimal set of functionalities these layers put together provide
...
13 Recommended Readings
1
...

3
...

5
...

7
...

9
...

11
...

13
...

15
...
O
...

C
...

Cisco staff: Internetwork Design Guide , Cisco Press / Techmedia, New
Delhi, 1999
...

Cormac Long: IP Network Design, Tata McGraw-Hill, New Delhi, 2001
...
Comer & D
...
Stevens: Internetworking with TCP /IP, Vols
...

D
...
-1, Third Edition, PrenticeHall, Englewood Cliffs, 2002
...

Garry R
...
): Handbook of Networking and Connectivity, AP
Professional, 1994
...
F
...
): Multimedia Systems, ACM Press, Addison-Wesley,
New York, 1994
...

Nalin K
...

R
...
Arora et al (Ed
...

Rahul Banerjee: Lecture Notes on Computer Networks, Oct
...
bitspilani
...
in/~rahul/csc461/index
...

2002,
BITS,
Pilani,
available
on-line
at:
http://www
...
ac
...
html/

1
...

2
...


4
...


6
...


What are the situations in which, you, as an intranet designer, would opt for
a Cell Switching Intranet technology?
Why is it more common to see Packet–Switched Campus-wide Intranets
than the Virtual Circuit-Switched Intranets of the same set of capabilities?
(An example is the popular preference to the Switched Gigabit Ethernet
backbones over ATM backbones in campuses
...
3 LANs, IEEE 802
...
x LANs with / to a high speed setup capable
of providing guaranteed quality of service for running heavy multimedia
networking applications
...
If the client demands that the proposed solution (to
be offered by you) should not force it to throw away its older LAN-oriented
application software, at least immediately, which internetworking technology
out of those discussed in this chapter would you propose and why?
Look up the Web for Packet Service Internetworks and comment on the
suitability of their application to the remotely located Indian rural areas for
supporting the Tele-Medicine applications
...
3x standard and the IEEE 802
...
In case
you have to integrate LANs based on these fixed and mobile networkingbased standards, how would you plan interconnection such that seamless
operation becomes possible at the user level?
Study the relevant IETF RFCs pertaining to the MPLS solution proposed
originally by Cisco
...


Chapter-2

The Multimedia Internetworking Technology Basics
Interaction Goals
Interaction Goals of this chapter include defining the Multimedia Internetworks,
identifying the fundamental components of Multimedia Communication,
understanding of Design Issues, Bandwidth Requirement Analysis of the Shared
Multimedia Applications, identification of the factors influencing Effective Link
Bandwidth, developing a conceptual understanding of working and applications of
Videoservers and a glimpse of current practices and future trends
...


Here, prerequisite is some exposure to Data Communication basics
...
1 Introduction
In the previous chapter, we have explored the world of internetworks and attempted to
pick up a few preliminary but fundamental concepts of associated technologies
...
We shall also take a good look at the design of
multimedia internetworks, related methodologies, architectures and technologies
...


2
...
These have been identified in the literature as:
q
q
q
q

Capability of media-based expression of information
Capability of effective use of various tools / means of articulation of a concept /
idea
Capability of reacting / responding in the real-time
Capability of collaborative communication

q

Capability of unicasting, multicasting (or anycasting) and broadcasting

Since most of the multimedia applications invariably focus on the human behaviour,
tolerance levels, adaptability, perception-patterns and intelligibility-characteristics, all
good multimedia internetwork designs need to model themselves on the abstractions
suggested above
...
3 Defining Multimedia Internetwork
An Internetwork of autonomous computers consisting of LANs and / or WANs, in which
(depending upon the specific context of use) it could be possible for two or more
participating entities to get an assured minimum quality of network service(s) during their
exchange of one or more components of multimedia data is called a Multimedia
Internetwork (MMI)
...
3
...
These include:
q
q
q
q
q
q
q
q

Desktop Videoconferencing over the Internet
Scheduled Video over Internetworks
Voice over Internetworks
Video-on-Demand over Internetworks
Multimedia-based Distance Learning via the Internet
(Virtual University models included)
Continuous-Media-based Digital Libraries
Collaborative Workshops over the Net
Telemedicine Consultancy via the Internet

We shall learn about most of these applications and their typical design requirements
from the MMI point of view in the subsequent chapters in adequate detail
...


2
...
There exist, however, several factors which, when monitored, give
an indication that the organization needs a multimedia-capable internetwork
...


2
...
In some of the situations, particularly those wherein

the problem lies with the poor usage o r configuration rather the hardware resources, it
may be possible to get an acceptable performance just by putting your head down and
tuning up the existing configuration or simply reallocation of resources
...
However, in majority of the cases,
selective upgrade may be a preferable approach
...
Steps that are normally helpful in systematic upgrade of existing
internetworks to partial or full-fledged MMIs include:
•
•
•
•
•
•
•

Analysis of Bandwidth requirements
Careful reallocation (preferably, dynamically) of network resources with the
help of a priority policy
Reconfiguration of the existing resources, if necessary
Statistical analysis of user history profiles and authorization for selective
priority based access control
Structured grouping / regrouping of users
Exploring the possibility of use of Intelligent Agents and / or Softbots
(Software Robots) for critical but frequent / repetitive tasks
...


2
...
The Time-Sensitivity
Analysis is, therefore, often a good way of moving towards a good MM Internetwork
design
...
) is often
necessary
...
Put together, all of these factors point
towards the need for some type of QoS assurance for such shared services
...
7 Multimedia Internetwork Integration
As stressed throughout this and preceding discussion, primary needs and preferred
features in an MMI integration include the capability to interoperate, exhibit stability, offer
transparency, inherit controllability, demonstrate reliability and provide a high degree of
availability -- and all this, without lowering of throughput and degree of service utilization
...
Security issues vary from situation to situation
and it should be remembered that often networks with adequate security by design might
prove insecure because of poor configuration or access-control policy
...


2
...

One of these is to consider the type of service-solicitation as the criteria for deciding a
class
...
9 Link based Classification of Multimedia Internetworks
MMIs can also be categorized on the basis of link classes
...
These
include:
q
q
q
q

Point-to-Point Unidirectional Multimedia Internetwork applications
Point-to-Point Bi-directional Multimedia Internetwork applications
Point-to-Multi-point Unidirectional Multimedia Internetwork applications
Point-to-Multi-point Bi-directional Multimedia Internetwork applications

Subsequent sections take a brief look at each of these classes and attempt to identify
select applications in each of the categories
...

2
...
1 Point-to-Point Unidirectional Multimedia Internetwork applications
Examples of Point-to-Point Unidirectional Multimedia Internetwork applications include:
•
•
•

One-way Teleconferencing with audio-callback
One-way Video-Multicast using a stored video stream
One-way Videoconferencing using a real-time stream

2
...
2 Point-to-Point Bi-directional Multimedia Internetwork applications
Examples of Point-to-Point Bi-directional Multimedia Internetwork applications include:
•
•
•
•

Two-way Audioconferencing
Two-way Videoconferencing (using real-time stream)
Online Multimedia-based Training (real-time)
Shared Whiteboard based Multimedia Collaboration

2
...
3 Point-to-Multi-point Unidirectional Multimedia Internetwork applications
Examples of Point-to-Multi-point Unidirectional Multimedia Internetwork applications
include:

•
•
•

Web TV
Non-Interactive Real-Time Video Stream based Multicasting
Non-Interactive Stored Video Stream based Multicasting

2
...
4 Point-to-Multi-point Bi-directional Multimedia Internetwork applications
Examples of Point-to-Multi-point bi-directional Multimedia Internetwork applications
include:
•
•
•
•

Interactive Video Distribution
Multiparty Videoconferencing
Video-on-Demand
Voice-on-Demand

2
...

Interaction over MMIs are influenced by many factors including but not limited to the
following:
q
q
q
q

Levels of multimedia information flow
Type and Volume of multimedia content
Number, Location and Frequency of entities involved in simultaneous
multimedia information exchange
Extent of Hardware and / or/ Software support required / available

2
...
Furthermore,
factors like the proportion / degrees of use of two or more of such objects in a two-way
or multi-party multimedia exchange influence the bandwidth requirements
...
Number of parties involved and their geographic locations affect
bandwidth requirements as well
...
Physical and logical organization of various multimedia servers
(like audio servers, video servers etc
...
Router / Switch hierarchies and the network / internetwork
topology also play important roles in this matter
...
The choice of Data
Compression and Decompression / Recovery Scheme plays an important role in all such
matters
...
12 The Bandwidth Factor
The maximum Rate of Data Transfer that a given transmission link may support, is
called its Maximum Bandwidth
...

The Effective Link-bandwidth actually depends on several physical factors like:
•
•
•
•

The transmission quality supported by a guided or unguided medium
The effect of proximity of adjacent signal frequencies
The type of physical terminators and /or connectors intended to use along
with the link
Effect of noise(s) and external interference(s)

Multimedia Traffic over an Internetwork may include one or more instances of:
q
q
q
q
q
q
q
q

Image (10 - 500+ Kbps)
Voice (4 - 100 Kbps)
Text / Data (<5 Kbps)
Stereo Quality Audio (125 Kbps - 1 Mbps)
HDTV Signals (200 Mbps - 1 Gbps)
VCR Quality Video (4 - 10Mbps)
3-D Scientific Visualization (around 1 Gbps)
Animation
< All of these values are approximate
...
>

Average degree of compression in each case is different and has a bearing on the
required bandwidth
...
54 Mbps)
Low Quality Compressed Video (100 Kbps)

In multimedia internetworks, the medium quality compressed video is often preferred
because it offers a good compromise between cost and quality
...

2
...
This provides a costly (medium to
high cost) but highly collaborative option and permits the participants to exchange,
modify, visualize and simultaneously view multimedia data that may be in the forms like
Graphs, Charts, Images, and Text etc
...
However, with the advancement of technology and the
anticipated economics of scale, these drawbacks are no longer the major barriers
...
Video-on-Demand technology is a related technology but may exist
with or without computer networks, though the former is more common
...
14 Videoservers
A Videoserver is a server that is specifically designed and configured for:
•
•
•
•
•

Handling efficiently and reliably video traffic over an existing network /
internetwork
...

Converting Analog Television signals (where so applicable) into digital video
signals
...

Providing linkage between various interacting components using its services in
a manner that is transparent to the participating clients
...
The exact amount of required bandwidth also depends on the
capacity and speed of various components like Video Camera(s), Video Capture /
Playback / Frame-grabber Adapter(s) and certain other factors including those
mentioned earlier
...
Like the factor of acceptable Audio Latency, Video Latency also
proves a major factor in bandwidth estimation as well as QoS-based Routing decisions
and that is why it is important to reduce latency and further take appropriate measures to
nullify the effect (jitter) generated by variable latency
...


2
...
In a commercial scenario involving hybrid media a typical
videoserver should be able to handle all the three formats on demand
...


q

Features 525 lines per frame and recommends 30 FPS (frames per
second) refreshing rate
...
)

The PAL (Phase Alternation Line) Standard:
q
Followed in India, several European countries, gulf countries and many
other countries
...

The SECAM (System Electronique pour Couleur Avec Mémoire) Standard:
q
Primarily used as the analog multimedia broadcast standard in France,
Russia and a few other countries
q
Features 625 lines and 25 FPS refreshing rate
...


2
...
As usual in the real-life situations, no single design or
design strategy, howsoever brilliant it may be, works well in all situations
...
One simple rule to keep in mind is that like in any
other engineering design, economics may, at times, dominate your final decision so
much so that a technically superior design may have to give way to a relatively inferior
solution
...
Often a two-pronged approach of step-wise
incrementing the quality and almost simultaneously assessing the associated cost helps
to avoid such situations
...

Technology helps
...
And, all this without any additional investment!
Cases of upgrade that really demand / warrant major changes are actually redesign
problems
...
Steps suggested in the chapter, therefore, can play a
very helpful role in these matters
...
This does not, however,
lessen the magnitude of the problem except for the fact that you, as a designer, may
offer a solution that may afford to reduce the price tag by slightly compromising on the
FTRT requirement of processing
...


2
...

2
...

4
...

6
...

8
...

10
...

12
...

14
...

16
...

18
...

20
...
O
...

C
...

Cisco staff: Internetwork Design Guide , Cisco Press / Techmedia, New
Delhi, 1999
...

Cormac Long: IP Network Design, Tata McGraw-Hill, New Delhi, 2001
...
Comer & D
...
Stevens: Internetworking with TCP /IP, Vols
...

D
...
-1, Third Edition, PrenticeHall, Englewood Cliffs, 2002
...

Garry R
...
): Handbook of Networking and Connectivity, AP
Professional, New York, 1994
...
Ghosh and S
...
1998, pp
...

J
...
Koegel (Ed
...

Marilee Ford et al: Internetworking Technologies Handbook, Third
Edition, Cisco Press / Techmedia, New Delhi, 2002
...
Sharada: Multimedia Networking, Prentice-Hall of India, New
Delhi, 2002
...
K
...
): Multimedia 98 --- Shaping the Future , Tata
McGraw-Hill, 1998
...
2002, BITS,
Pilani,
available
on-line
at:
http://www
...
ac
...
html/
Rahul Banerjee: Lecture Notes on Internetworking Technologies, Oct
...
bitspilani
...
in/~rahul/eac451/index
...
18 Exercises
1
...


What are the situations in which, Jitter as well as Latency need to be
minimized appreciably? How shall you overcome the Jitter in an Intranet,
which is frequently used for heavy multi-party multimedia applications?
Consider a situation in which your client, a large university wishes to
upgrade its entire existing intranet to a high-speed setup capable of
multimedia networking
...
What
shall be your primary design choices in this case and why?
3
...

4
...

5
...
More often than not, generic file-systems exhibit their
inherent efficiency in this regard and make the latency problem more
severe
...
Identify such groups over the Web and study their findings
...

6
...
and why these styles need
to be preserved even when these objects are used together in a networked
environment?
7
...

How can we apply the Ethernet technology, if at all, in IPv6-based timesensitive Intranets?
9
...
Video Telephony typically uses a low frame rate (ray 10-15 FPS) and a
small picture – size
...
Why?
11
...
Why?
12
...
544 Mbps, 6
...
70 Mbps and
274
...
All of these use TDM principle
...
Which data-compression standards can be used for
this purpose and why?
13
...

Please note that in all cases, you may first compute the raw bandwidth
requirements and subsequently reduce this raw figure to a realistic value by
suggesting employment of one or more appropriate Data Compression
scheme
...
Naturally, a good understanding of fundamentals, a brief
study of impact of compression and decompression on internetworking
applications including the continuous media-based ones and a quick look at the
current practices and evolving trends form the basic content that is expected to
be assimilated
...

The treatment assumes a sound knowledge of data structures, time and space
complexity analysis and mathematical theory of transforms
...
1 Introduction
In comparison to the normal time-insensitive traffic, the multimedia traffic over
internetworks has its own set of requirements and these specific needs range from MMspecific Data Representation, Manipulation, Transmission, Storage, Management to
MM-specific Retrieval
...


A natural requirement of such traffic, as discussed earlier, is to have a continuous as
well as steady flow of stream of multimedia data
...

All these requirements put together have necessitated specialized technology solutions
for such traffic right from reception to storage, retrieval and transmission
...


3
...

(Theoretically, both space and time compressions are attainable
...
) In an Internetwork, careful compression
is essential for acceptable throughput
...

Majority of the video-data compression schemes employ mathematical algorithms for
smoothing out the minor / finer details within the original video-data those are not
recognizable by the naked human eye
...

There exist two primary classes of Data Compression: Lossy Compression and Lossless
Compression
...
Yet another way to categorize compression may be
based on the manner of compression within or between the successive video-frames;
and may lead to two basic classes: Intraframe Compression and Interframe
Compression
...
3 Lossy versus Lossless Data Compression
As suggested in the foregoing discussion, there are two broad classes of any form of
compression:
•
•

Lossy Compression (e
...
JPEG compression)
Lossless Compression (e
...
RLE compression)

Certain situations that may tolerate some degree of information loss are best suited to
the Lossy Compression schemes
...
3
...

3
...
2 Lossy Compression
In case, the scheme / algorithm works such that while storing the information in the
chosen compressed format, it does leave out certain pieces of it; and, even the
decompression scheme / algorithm cannot retrieve the information-content of the entityin-question to its original form, the compression technique is called Lossy Compression
Technique
...
4 Graphics Metafiles
A graphics metafile is often a file that provides storage / space compression by
describing the graphical details by using Meta tags / descriptive notations
...
For instance, the
description: Square 20,2,38 may refer to a square which is anchored at the screen
coordinate (20,2) and which has width as well as length 38 pixels
...
Not all graphics may be expressible in so simple a manner though!

3
...
Any / all of these redundancies can be
exploited to obtain varying degrees of compression of textual documents
...
6 Primary Classes of Data Encoding Techniques
3
...
1 Entropy Encoding: This is a lossless encoding technique that does not make any
distinction between data-bits on the basis of its characteristics
...
6
...

3
...
3 Statistical Encoding / Arithmetic Compression Technique
In this case, the given textual data / file is analyzed and a Concurrence Table (i
...
a
table of repetitive usage) is generated for select patterns (of sequence of characters)
and thereafter using a specifically designed compressed representation format every
such occurrence is encoded (normally, with lesser number of bits)
...
6
...
e
...


One such technique is the Run Length Encoding (RLE) technique, in which any such
repetitive sequence / character is replaced with a flag followed by the number of
repetitions which is further followed by the original bit-sequence / character that was
found to be repeated in succession in the original data
...
6
...
(A continuous audio signal or a motion video is a good example of such a
case
...
6
...
Important / strongest
coefficients are encoded precisely and less important / weak coefficients are often
encoded with less precision in such Transform Encoding cases
...
6
...

Pure Huffman Encoding: This involves use of a variable length code for each of the
elements within the information
...

3
...
8 Adaptive Huffman Encoding
This variation was first suggested by Faller and Gallager and subsequently modified by
Knuth
...
Unlike its pure version,
the adaptive version provides optimal encoding by adapting the encoding process as per

analytical statistics of a piece of data
...
Also, only one pass scan is adequate in this case
...

3
...
9 The Lampel-Ziv Encoding Techniques
These techniques make use of Adaptive Dictionary-based Data Compression Schemes
...
In this scheme of compression the first step is to locate type and frequency of
repetition
...
)
A special identifier called F lag’ is used for distinguishing compressed data from
’
uncompressed data
...
3
...
6
...
Its
basic idea is to locate the type and frequency of repetition (this repetition may be in
many of the binary repetitions or textual repetitions (includes letters / words etc
...


Storage or transmission of this dictionary, as the case may be, before decoding the
compressed data is necessary in this scheme
...
In most of the
practical implementations of this scheme dictionary size is 4K or above
...
The encoding scheme depends in a way on the
dictionary size as well
...

3
...
11 The V
...
In 1990, ITU accepted it under the name V
...
This compression scheme
had the following characteristics that made it suitable for use in dial-up Modems:
•
•
•
•
•
•

It can be easily implemented on 8/16-bit microprocessors
...

It has incorporated its dictionary-size including its codeword notation as
well as representation scheme
...

Control codes 0, 1 and 2 are reserved
...


Due to the provision ‘1’, the initial stings are required to be indicated by the indices 3
through 258 (instead of the default 0-255)
...
The data structure supported in this
case is the Trie data structure
...
e
...
42 bis / BTLZ scheme is
depicted below
...
-> | Character | Parent | First child | Dependent |
3
...
11
...
The V
...

3
...
12 Discrete Cosine Transform based Compression Scheme
This is conceptually similar but technically superior to the well-known Fast Fourier
Transform (FFT) based compression scheme in terms of speed of convergence as well

as compression ratio
...
The JPEG
(Joint Photographic Experts Group standard), MPEG (Motion Pictures Experts Group
standard), H
...

There are two basic forms of the DCT; namely, Forward Discrete Cosine Transform
(FDCT) and Inverse Discrete Cosine Transform (IDCT)
...
As a result, for more MM-heavy MMI applications, improved techniques /
schemes are being investigated / evolved
...
6
...
It does not provide, however, any spectacular performance improvement over
the latter! Unlike the DCT, this scheme uses Pixel blocks of smaller size for fine detailing
of the relevant video-data-area and Pixel blocks of larger size for the coarse detailing of
the visually less relevant data-area
...

3
...
14 Fractal Compression Scheme
The term Fractal has its origin in the phrase “Fractional Dimensional”, a phrase
commonly used in the world of mathematics for referring to a fractional element of a
graphic object generated by repetitive application of a compression algorithm until the
point of convergence is reached and the algorithm terminates
...
This results in
smooth degradation of the graphic image
...
The root of this interest is the potential
compression ratio that, at least theoretically, is one of the highest offered by any other
scheme – a theoretical upper limit of 10000:1 has been computed – practically,
compression ratio of the order of 2500:1 has been possible to achieve!
This scheme, like many others, is an Asymmetric Data Compression scheme, as it
requires greater time in data compression than the decompression
...
6
...
It was originally developed at the Saruff Laboratory of the Radio
Corporation of America (RCA) and subsequently improved by the IBM Corporation and
Intel Corporation
...
It offers Production-Level Video (PLV) compression ratio of
the order of 120:1 that is a remarkable feature
...
Downside of this technology is its very high computing needs due to which it
could not be popular with most of the less demanding MMI applications
...
6
...
261
are some other well-known solutions offered for video-data compression
...
Pure Software
Codecs often provide smaller video-window sizes for acceptable resolution; therefore,
Full-Screen True Colour Motion Video often requires the hardware support of the said
type
...
For instance, the Real Video offers Fractal Compression based
streaming solution whereas many other Software Codecs use one or other form of
Vector Quantization based compression
...
7 The GIF Compression
The term GIF stands for the Graphics Interchange Format
...
This format was
popularized by the CompuServe in the eighties and is a commonly used scheme for
encoding still images in normal, interlaced and animated forms
...
3
...
It can be
briefly described as below:
• Initialize the string table;
• [Start-prefix] = Null;
• NextChar = next character in character-stream;
• Is [Start-prefix] NextChar present in string table?
o If yes: [Start-prefix] = [Start-prefix] NextChar; go to Step-3;
o If no: add [Start-prefix] NextChar to the string table;
o Write the code for [Start-prefix] to the code-stream;

•

o [Start-prefix] = NextChar;
Go to Step-3;

The definition of the GIF Format includes a Data Stream comprising of the Header, the
Logical Screen Descriptor, a Global Color Table and the GIF Trailer
...
e
...

6-Byte GIF Signature
8-Byte Screen Descriptor
Global Colour Map

10-byte Image Descriptor

M

I

0

0

0

Image Separator
Image Left
Image Top
Image Width
Image Height
Pixel
Local Colour Map
Raster Data
Byte-0: LZW Code Size
Byte-1: Block-1 Size
Data Bytes
…
...


B
l
o
c
k
N

Block Terminator

GIF Terminator

Fig
...
2: The GIF Format

3
...
It was based on a W3C
recommendation document for still images
...

The PNG scheme is a combination of two schemes: Predictive Encoding Scheme and
Entropy Encoding Scheme
...
9 The JPEG Compression
The term JPEG stands for the Joint Photographic Experts Group
...
The original JPEG was a DCT-based scheme and had following
modes:
• Lossless Mode
• Lossy Mode
• Baseline Mode
• Progressive Mode
• Hierarchical Mode
JPEG uses a set of algorithms some of which are interchangeable in terms of
functionalities of compression category and quality
...
There are several variants of JPEG based on these modes and
a few small enhancements
...

The latest addition to the JPEG-family is the JPEG-2000
...
This uses a variant of the Wavelet
Transform called Discrete Wavelet Transform (DWT)
...
It offers a low bit-rate compression (< 0
...


3
...
This is a layered encoding
scheme that comes into a variety of flavours and versions including the following:
•
•

MPEG-1
MPEG-2

•
•
•

MPEG-4
MPEG-7
MPEG-21

Standards like MPEG-1, MPEG-2, MPEG-4, MPEG-7 and MPEG-21 belong to the
Continuous Media category of media objects
...

The popular audio format MP3 actually stands for MPEG-1 (Audio) Layer-3
...

Whenever two or more multimedia objects need to be embedded, they need to
synchronize their time-presentation styles
...
For network-oriented applications, not only
such temporal relations and their embedding schemes play important roles but also their
data-compression mechanisms / algorithms / formats do matter in a big way
...
Still Images, Textual data are the examples of Time-Independent
Media Objects
...
One has been withdrawn later
...

Like its predecessors, MPEG-4 standard is also a multi-part standard (ISO/IEC 14496x)
...
It uses
a two-layer multiplexing scheme so as to be able to exploit the Quality-of-Service (QoS)
provided, if any, by the underlying internetwork
...
Artificially
Generated Interactive Graphics and Distributed Interactive Multimedia
...
It has the capability to describe visualization of a complex scene
comprising of hierarchy of a variety of media objects
...
These efforts have resulted in a
framework standardized in the document ISO/IEC 14496-8 that is often seen as an
broad specification for the transmission and use of MPEG-4 sessions over IP (Supported
protocols, as usual include the RTP, RTSP, UDP, HTTP etc
...
MPEG-4 standard has the following
eight parts:
§
§

§

§
§
§
§
§

ISO/IEC 14496-1 (Systems)- It has tools including BiFS, Object
Descriptors, FlexMux, MP4 File Format etc
...

ISO/IEC
14496-3
(Audio)It
has
specification
for
Speech coding, General Audio Coding, Structured Audio, Text to Speech
interface, Parameteric Audio etc
...
MPEG-21 is currently under evolution and it
aims at defining an open framework for multimedia delivery
...
11 Summary
Specific needs of the MMI-specific applications range from MM-specific Data
Representation, Manipulation, Transmission, Storage, and Management to MM-specific
Retrieval
...


Many solutions to this set of requirements have been suggested
...
Pure Software Codecs often
provide smaller video-window sizes
...
261
are some of the popular video compression solutions
...
MPEG-4 is a multimedia representation standard that models
audiovisual data as a composition objects
...
The MPEG-7 standard, called as the “Multimedia Content Description
Interface”, provides standardized tools for description of multimedia content
...
12 Recommended Readings
1
...
1996
...
D
...
Ebrahimi, J
...
Larsson and C
...
(Status: Informational document) This is based on two
papers:
• D
...
Ebrahimi, J
...
Larsson and C
...
Vol
...

• D
...
Ebrahimi: An Analytical Study of JPEG 2000
Functionalities
...
ISO/IEC: JPEG 2000 Image Coding System: Core Coding System, WG 1 N
1646, March 2000, available at the URL: http://www
...
org/FCD15444-1
...

4
...
1999
...
W3C: PNG (Portable Network Graphics) Specification, Oct
...
w3c
...

6
...
1999
...
ISO/IEC: Information Technology – Coded Representation of Picture and
Audio Information – Progressive Bi-Level Image Compression, May 1993
...
Bohdan O
...

9
...
Sharda: Multimedia Information Networking, Prentice-Hall New
Jersey, 1999
...
13 Exercises
1
...

2
...
and compress them after
digitization
...

Survey the Codec product sites and identify five major Codecs that claim to offer
the video quality comparable to the high quality of the broadcast TV services
...
NI-GIF, I-GIF and Animated GIF have come out of a common GIF format
...

4
...

5
...

Some of these parts have modifications issued on later dates, latest one being
introduced as recently as 1999
...
Discuss the internal functional structure of the ISO/IEC 11172-x Encoder and
Decoder with the help of necessary diagrams and briefly comment on the
Temporal MPEG-1 image structure
...
MPEG-2 standard is currently a nine-part standard (ISO/IEC 13818-1 through
13838-10: one part being withdrawn)
...

8
...

9
...

At the end of this chapter, you should be able to:
• Identify the situations wherein Softbots, Centralized Agents, Distributed
Agents, Mobile Agents and their Intelligent counterparts may be costeffectively used,
• Select the right Agent technology for the right occasion,
• Understand the performance and security trade-offs involved in certain
combination of technologies
...


4
...
These may be
often small in size and get automatically into an action whenever the associated events
take place or even in a pro-active manner, at times! These are not Operating Systems or
top-level applications but merely intermediaries called Agents
...


4
...


An Intelligent System is often a knowledge -based multi-agent system
...
3 Intelligent Agents
An Intelligent Agent is an entity that may be used to accomplish a set of pre-defined
tasks in a manner that may be transparent to the applications and user and which may
involve handling known, partly known or unknown situations
...
The overall
distributed artificially intelligent system, in such a case, becomes simply a co-operative
collection of individual modules that interact with one-another for solving a complex but
ill-structured problem
...

As referred above, an Agent may be of non-intelligent type or of intelligent type; and, in
general may be seen as belonging to one of the following basic classes:
• Gopher Agents
• Predictive Agents
• Service Agents
• Leader / Pro-active Agents
• Adaptive Agents
Simple Gopher Agents act as an intelligent or non-intelligent interface agent that may,
for instance, act as appointment tracking and alerting system
...
Webbots,
Taskbots, Userbots, Schedulerbots etc
...

Data Mining Agents and Intelligent Monitoring Agents are the examples of the Predictive
and Proactive Agents
...
are other possible agents over the Internet
...
Jobots are Job-search Agents, Newsbots are
meant to collect relevant news and Hotbots are used to locate 'predefined' category of
so-called 'hot' content pages / sites (what is treated as hot may vary from situation to
situation)
...
Docbots are used to locate Medical Doctors on-line, Javabots are
employed to locate Java Applets over the Net and Annoybots are used by the malicious
attackers for creating annoyance / disruption
...
Anderson Consulting's
'BargainFinder' and Excite's 'Jango' are examples of Shopping Agents / Shopbots
...
4 Attributes of Intelligent Agents
Intelligent Agents are expected to display certain degree of autonomy and must exhibit
an appropriate sub-set of following behavioural attributes depending upon the goal(s) of
the respective agent:
•
•
•
•
•
•
•
•
•
•
•

Ability to act at its own
Capability to respond to a situation
Capability of taking Initiative
A subset of what is perceived as Human Intelligence
Goal Directed Behaviour
Network / Internetwork Mobility
A subset of what is perceived as Rationality
Selectivity and Interactivity
Fault-tolerance
Avoiding propagation of false data / information
Capability of avoiding conflicting goals of other Agents where
possible

4
...

Deliberative Architectures
Agent architectures based on explicitly represented symbolic models and well-defined
courses of action for each of the specified goals belong to this class
...
Such
agents often use logical / symbolic reasoning schemes
...

Hybrid Architectures
These architectures inherit properties from both of the above-referred classes of
architecture
...


4
...
4 and 4
...
These include the following:
•
•
•
•
•
•
•
•
•

Network / Internetwork Monitoring
Traffic Management
Security Management
Privacy Management
QoS Management
Failure Management
Response Customization
Pro-active Marketing
Access History based disaster avoidance

4
...
In most of the real-life situations in the world of Multimedia Internetworking,
an Agent is used because of several reasons including the following:
•

•
•
•
•
•

Many applications are inherently distributed and therefore, they are not well
suited to a centralized scheme of things
...

Since the work is distributed amongst the individual Agent’s architectural and
structural modularity becomes an inherent feature of such systems
...
In other words, system often responds faster than before!
Higher efficiency is another motivating factor for use o f Agents in most of the
cases
...

Higher degree of reliability and robustness provided by a set of well-designed
Agents often reduces the cost of maintenance in unattended application
segments
...
8 Components of IA based Distributed Systems
Intelligent Agents are the integral parts of Distributed Reasoning Architectures
...
9 Other Aspects of Intelligent Agents
Centralized Assignment Decomposition scheme based implementations involve the
following stages by the Supervisory Agent:
• Problem Analysis,
• ‘Agent Capability Analysis / Survey’ and ‘Load-balancing’,
• Decomposition of the Problem / Assignment,
Assigning different parts of the assignment to individual Agents (I
...
suggesting subgoals of the overall goal to various Agents),
• Synchronization of distributed tasks,
• Collecting results of individual task -executions
...


4
...
The Java Aglet technology effectively extends the model of mobile (over the
network / internetwork) code already witnessed in the Java applet technology
...
Since an Aglet carries its state, it can
travel, as directed or required, to many destinations on a network and may even return
to its point of start of journey
...
An Aglet needs a
host Java application called as Aglet Host, executing on a computer / node for visiting
that computer / node
...
Each Aglet host installs a security manager to enforce restrictions on the
activities of untrusted Aglets
...

An Aglet may be:

•
•
•
•
•
•
•

Created
Cloned
Dispatched
Retracted
Activated
Deactivated
Disposed of

Aglet hosts use object serialization, available in JDK / SDK with the RMI (remote method
invocation) add-on, to export the state of an Aglet object to a stream of bytes
...
The Aglet-state can be reconstructed from the stream of bytes
...
Object serialization uses only data on the heap
...

Unlike expectations of the theoreticians interested in the behaviour of Classical Mobile
Agents, Aglets are incapable of retaining their state after cloning etc
...
This behaviour of Aglets is due to the architecture of the JVM, which
doesn't allow a program to directly access and manipulate execution stacks
...
Unless there is a change to the JVM, Aglets and any
other Java-based mobile agents will be unable to carry the state of their execution
stacks with them as they migrate
...
Aglet may be modeled as an FSM with
the heap as the only carrier of the state
...
To create an Aglet, we have to subclass class Aglet
that includes methods, which can be overridden to customize the behavior of an Aglet
...
To
initialize an Aglet, onCreation() is overriden
...
The Aglet also has a
run() method representing the entry point to its main thread
...
An
Aglet learns about its serialization just ahead of its use
...
An Aglet can invoke dispatch() on itself or on another Aglet, with
due authorization
...
11 The Stanford’s JAT Technology Architecture
The Agent building has come of age now although the technology is still evolving very
rapidly
...
The JAT Lite tool developed
at the Stanford University is one of the earliest generic agent creation tool-kits
...
It aims at
providing an infrastructure that may be interpreted as:
q
q
q
q

a programmer’s workbench,
an AMR (Agent Message Router) facilitator,
an execution and debugging environment,
a KQML based communication facility
...

Like the Aglet Development Tool-kit, the JAT Lite can run on any JDK / SDK supporting
platform
...

As shown in Fig
...
1, the JAT Lite Architecture is a five-layer architecture:
•
•
•
•

•

The Abstract Layer is responsible for making the abstract classes required for
implementation
...

The KQML Layer is responsible for providing support for KQML-specific message
generation, parsing, validation, storage and retrieval
...

The Router Layer, as the name rightly suggests, is primarily responsible for
routing Agent Messages
...

The Protocol Layer is primarily responsible for providing higher-level protocol
support as may be necessary for any given Inter-Agent Communication over the

Internet, intranets or extranets
...


Protocol Layer
Router Layer
KQML Layer
Base Layer
Abstract Layer
Fig
...
1: The Stanford’s JAT Architecture
4
...
Unlike the Stanford JAT, it is particularly suitable for the Carl Searle’s ‘SpeechAct’-based Multi-Agent Systems
...
The JAFMA, like the JAT, provides a general
purpose Agent development support
...


4
...
Due to recent impact of
the Business AI, a renewed interest in internetworking agents of ordinary as well as
intelligent classes is being witnessed at present
...
Java-based
agents are fast becoming developers’ choice
...

An Intelligent System is often a knowledge-based multi-agent system
...
Service Agents are explicitly designed to
perform specialized services
...

Principal Intelligent Agent architectures can be roughly classified as Deliberative,
Reactive and Hybrid Architectures
...
Such agents often use logical / symbolic reasoning schemes
...
Intelligent Agents are the integral parts of Distributed
Reasoning Architectures
...

The acronym JAFMAS stands for the Java-based Agent Framework for Multi-Agent
Systems
...

Agents have been used in networking applications since ages
...


4
...

2
...

28
...

5
...

7
...

9
...
Amandi and A
...

B
...

B
...
72, No
...
329-365
...
Pell: Agent Architectures for Autonomous Control Systems, Tutorial at
the PAAM ‘97 Conference, London, 1997
...
Quendt: An Agent-Based Resource Control of the Signaling System for
the Open Telecommunication Market, Proceedings of the PAAM ‘97
Conference, April 1997
...
Leckie et al: A Multi-Agent System for Distributed Fault Diagnosis,
Proceedings of the PAAM ‘97 Conference, London, April 1997
...
Martin et al: Information Brokering in an Agent Architecture,
Proceedings of the PAAM ‘97 Conference, London, April 1997
...
Pinnard, M
...
Gray: Issues in Using an Agent Framework for
Converged Voice / Data Applications, Proceedings of the PAAM ‘97
Conference, London, April 1997
...

H
...
Bussmann and M
...

29
...

12
...

14
...

16
...

18
...

31
...

20
...

22
...

23
...

25
...

J
...

J
...

J
...
Kendall and T
...

J
...
Whatley and P
...
A
...

John Fox: Intelligent Agents Which Reason About Beliefs, Decisions and
Plans: Logical Foundations and Practical Applications, Invited Paper, PAP
‘97 Conference, London, April 1997
...

N
...
Mathieu: A Hybrid and Hierarchical Multi-Agent
Architecture Model, Proceedings of the PAAM ‘97 Conference, London, April
1997
...
R
...
of London, 1995
...
)
P
...

P
...
Rossi, F
...
Knoche and R
...

Pattie Maes: User-facing Software Agents, Tutorial at the PAAM ‘97
Conference, London, 1997
...
demon
...
uk/ar/PAAM99/
Rahul Banerjee: An Intelligent System for Behavioral Analysis, Ph
...

Thesis, AU, Amt
...

Raj R
...
27, No
...
301-303
...

S
...

T
...
Dahl, S
...
W
...

Tim Finin: Agent Communication Languages: KQML, KIF and the
Knowledge Sharing Approach, Tutorial at the PAAM ‘97 Conference,
London, 1997
...
Braun, B
...
Wendler: Service Definition of Intelligent
Networks: Experience in a Leading-edge Technological Project Based on
Constraint Techniques, PAP ‘97 Conference, London, April 1997
...
V
...
Sarma: Intelligent Agents, Journal of IETE, Vol
...
3, 1996, pp
...

Y
...


4
...

2
...


4
...

6
...


Design and implement a User Agent for any well-defined Data Mining
purpose
...

What are the situations in which you would use both: IBM’s Aglets and
Stanford’s JATLite-based Agents and why? You may consider any Internetbased solution that shall benefit from their co-existence
...
In which manner shall the JAFMAS
technology be applied herein?
Explain the architectural details of the IBM’s Aglet technology in contrast to
that of the JAFMAS
...


Chapter-5

The TCP/IPv6 Internetworking Architecture
Interaction Goals
Interaction Goals of this chapter include developing an understanding of the
internals of the TCP/IPv6 Architecture involving the Transmission Control Protocol
(TCP) and Internet Protocol Version 6 (IPv6) from a designer’s perspective
...
We shall also take a quick look at the accepted
industry practices and evolving trends
...

Compare the TCP/IPv4 and TCP/IPv6 stacks
...


The prerequisites are some exposure to networking environments and
components
...
1 Introduction
Gone are the days when the term Internet referred to an internetwork connecting
Computer Science departments of select privileged universities and the Advanced
Reseat Project Agency of the U
...
Department of Defense
...
The TCP / IP architecture owes its architecture to this rich heritage
...
Yes,
even as you read this piece, IP or IPv4 in its three-decade old form (the Internet Protocol
Version 4 is often called IPv4 or simply IP as described in the RFCs 760 and 791), rules
the world
...

Though proposed originally much earlier, by different people in different forms, it may
take quite some time before the world really talks IPv6
...
The list is long
...
Not many people view
the ATM technology as a threat for the IP technology
...

5
...
Each of these layers has its well-defined set of functionalities
...
)
Transport Layer (TCP/UDP etc
...
)
Host-to-Network Interface

Fig
...
1 The TCP/IP Architecture
5
...
1 The Application Layer
The Application Layer is responsible for a set of functions commonly required by various
applications
...
Examples of
some application layer protocols include protocols like HTTP, FTP, Telnet and TFTP etc
...
It can offer both, connection-oriented as well as
connectionless services
...
2
...
It is responsible for receiving the data
from the upper layer (AL) and, if so needed, dividing it into manageable chunks for the
purpose of further processing and onward transmission via the IP Layer after prefixing its
own header to the processed data
...
Other activities of this layer include creation of network connections as per
the transport connection requests by the upper layer
...
(Fig
...
2 and Fig
...
3 show the header structures
of the respective protocols
...
5
...
5
...
2
...
In IP terminology, a Network Layer Data
Unit (NLDU) called a Packet
...


In a nutshell, packet handling, packet management, Routing are the major
responsibilities of t e Internet Layer
...
However, in the TCP/IP Architecture,
connectionless services have been mandated for the IP Layer and this choice
has been shifted to the upper layer
...

Architecture and internal organization of the Internet Layer to be able to meet
the design goals: In this case, the real issue is choice of the mechanism that

•
•
•
•

would satisfy the primary design goals
...

Choice of Security to be provided at the subnet level: Choices here may
include optional or compulsory support for encryption and authentication
...

Choice of support for Quality-of-Service (QoS) and Faster Than Real-Time
(FTRT) processing: These choices are to be made based on the intended
class of applications
...
2
...

For instance, this is may be seen as an interface that sits between the IP and underlying
IEEE 802
...
3, IEEE 802
...
5 and IEEE
802
...
)
The Physical Layer inside the NIC is responsible for receiving the data from the Data
Link Layer, converting it into equivalent signal (representing the data in bits) and
transmitting these signals in the desired manner over a shared or dedicated
transmission link
...
Issues like physical
connection establishment, direction of transmission, frequency usage and other
procedural matters are under its purview
...
This
operation is reversed at the receiving end
...
in case of shared media systems
...
3 The Internet Protocol
The Internet Protocol (IP) Layer is responsible for receiving the data from the TCP / UDP
Layer, process it for finding out the required resources, if required -- divide the data into
fragmented units, decide the route to be taken by the respective data units and passing
the data to the underlying Host-to-Network Interface after prefixing its own header to it
...
Routing
decision can be based on a fixed / static routing policy or a dynamic (situation
dependent) routing policy
...
IP
Layer offers only a connectionless service
...
The IP has been a case of immensely successful protocol that has gradually
matured to deliver support for a variety of features, like support for optional encrypted
payload, optional IP-level authentication, mobility-extension, stateless address
autoconfiguration (in the latest version of the IP) etc
...
In fact, in the latest version of the IP, better known as
IP version 6 or simply IPv6, provision has been made to permit optional quality-ofservice by inclusion of flow-specification field (although, as of this writing, standard
specification of the FL usage is yet to emerge)
...


IHL

Type of Service

Identification
TTL

Flags

Protocol Type

31

Total Length

Fragment Offset
Header Checksum

S o u r c e A d d r e s s ( 3 2 -bit)
D e s t i n a t i o n A d d r e s s ( 3 2 -bit)
Options+Padding

Fig
...
4: The IPv4 Header Structure
IPv4 Field Name
Version
IHL / HLEN

Length
in bits
4
4

Type of Service (TOS) 8
/ DS
ignored by the
routers
...

Header length= IHL*4
...

Now: [6+1+(1)] bits referred to Differentiated Service
Classes, Cost-minimization bit and unused bit as
sub-fields
...

For packets > 64 K, this offset helps in reassembly
...

Specifies about the next protocol header
immediately following this header
...


Table-5
...
3
...
5
...
As shown in Fig
...
5, the Option sub-field is divided
into three parts: the 8-bit Code field (a 1 -bit Copy subfield, a 2 -bit Class subfield and a
5-bit number subfield), an 8 -bit Length field and a variable-length Data field
...


5
...
2 IPv4 and the World of Classes:
In the IPv4, any address is 32-bit long and is represented in four parts of one byte each
separated by decimal points or dots
...
) There exist two ways of looking at the IPv4
world: Class-based or Classful view (Classes: A, B, C, D, E) and Classless view
...
In the class-based version, the classes are designated based on the
first few bits of the Network Address portion of the IP address
...

0 Network Address
10
110
1110

Host Address (3-octet)

Network Address

Host Address (2-octet)

Network Address

Host Address (1-octet)

Multicast Address
Fig
...
5: Four Major Classes of IPv4 Addresses
(Class-E, with prefix 1111: reserved, not shown here)

In Class-A address, the first byte constitutes the Network Address and remaining three
bytes constitute Host Addresses
...
In Class-C
address, the first three bytes constitute the Network Address and the remaining byte
represents the Host Addresses
...
0
...
3, (Network Address:12
...
0
...
0
...
3
...
16
...
1
Example of a Class-C address: 192
...
7
...
0
...
0
Class-B Address Range:

127
...
255
...
0
...
0
Class-C Address Range:

191
...
255
...
0
...
0
Class-D Address Range:

223
...
255
...
0
...
0
Class-E Address Range:

239
...
255
...
0
...
0

-

247
...
255
...
3
...
A Subnet Mask is a sequence of bits that is used to separate Network and
Host Addresses from each other
...

Types of Subnetting:
n

Fixed-Length Subnetting / Basic Subnetting

n

Variable-Length Subnetting

Natural Masks
n
n
n

Natural Mask for Class-A: 255
...
0
...
255
...
0
Natural Mask for Class-C: 255
...
255
...
Every LAN segment is usually associated with at least one network
number (more are possible) and if no subnetting is done, only one segment can use a
given network address
...
All masks have a string of ‘1’s to the left and string of
‘0’s to the right
...
The basic
idea behind the CIDR are two: (a)- Allocation of the unallocated set of Class-C IPv4
network addresses in variable-sized address blocks; and, (b)- While allowing ‘a’, in effect
allocating contiguous Class-C IPv4 network addresses
...
If a
router ‘X’ get a packet that belongs to the IPv4 addresses of one these four zones, the
packet is simply forwarded to the zonal gateway
...

Two ways to represent the same CIDR address are :
n

199
...
0
...
28
...
0 255
...
0
...
are often used
interchangeably in the IPv4-CIDR literature
...
These IPv4 Addresses having special meaning include 0
...
0
...
255
...
255 denoting the local network broadcast
address, 127
...
y
...

5
...
4 On the Internet Control Message Protocol (ICMP):
During the normal operation of the Internet, many a times, errors, crashes and some
other unexpected events may occur
...
ICMP is a protocol that
is practically inseparable from the IP as both go together
...
5
...
If an IP header
is followed by an ICMP Message as its payload, the Protocol Type field of the IP header
shall carry a code of ‘1’
...
5
...

5
...
5 On the Internet Group Management Protocol (IGMP):
Like the ICMP, until the version 4 of the IP, another companion protocol known as
Internet Group Management Protocol (IGMP) was designed to support group-based

applications at the network level
...
By itself, IGMP is not a Multicast Routing
protocol
...
5
...
IGMP messages are transmitted
as payload of the IP header
...

In the latest version of the IP, the accompanying ICMP has been extended to provide
these functionalities and thus IPv6 and ICMPv6 put together take care of the functions
that were handled by IP, ICMP and IGMP
...
3
...
For
the purpose of actual delivery of a packet, the packet has to be sent through the Host-toNetwork layer which means, for actual transmission the association of a given IP
address to the lower layer address (say an Ethernet address / MAC Sub-layer Address)
is required
...
e
...
This is a stateless protocol and does not require any address servers
...
Fig
...
7 below shows the format of an ARP data unit
...
g
...
3)
Sender’s Protocol Address (SPA)
Variable-length (e
...
Sender’s IP Address)
Target Hardware Address (THA)
Variable-length (e
...
48-bit for IEEE 802
...
g
...
5
...
g
...
x frame) and transmitted over the LAN
...
3
...
The protocol that permits a
machine holding its lower layer address (say its Ethernet Address) to enquire about its
associated IP address is called the ‘Reverse Address Resolution Protocol’ (RARP)
...
Like the ARP, here too,
the query can be responded simply through a query-broadcast over the LAN and replyunicast cycle
...
In
case, there exists a statically configured setup, these protocols are not used
...
3
...
It is the result of deliberations of a special IETF workgroup and has been described in
the RFC
...
, Network Number
and Host Number
...
The problem of discontinuation of service would arise as soon as soon as the MH
moves out of its Home Zone; since now, the Routers would still continue to send traffic
meant for this MH to the Home LAN address they have in the know of!
One solution to this problem could have been assigning a new IP address to this MH
once it moved away from its Home Zone
...
Given the large amount of
transactions and inconvenience involved in implementing this solution and increasing
number of people using the MHs, this would translate into a huge network traffic /
bandwidth requirement by itself
...
plus
Network Address
...

Clearly, any acceptable solution had to avoid these traps and at the same time should
have provided the required mobility, along with the continuity of communication at an
acceptably low cost and without forcing the existing software to undergo any major
change; and, thus the Mobile IP was born!
Now, just because the Mobile Hosts are to be accommodated, the Stationary Hosts

should not be required to make any change in their local software
...
Databases and other collaborating entities
should not need to be explicitly informed of the changed identity of the MH
...

As a consequence, an important goal of not assigning a new IP address to the MH was
added to the IETF-WG list
...
This HA / HAA
should be in charge of keeping track of which MHs of its home network are currently
visiting a foreign network zone; and providing support services to these MHs as per
need
...
This FA / COA should be responsible for identifying the visiting
MHs, keeping their track, authenticating their credentials by communicating with the
corresponding HA / HAA and providing support services as per need
...
The response to this ARP broadcast then comes from the HA / HAA, which
supplies its address to the enquiring Router
...
Once the packet is
received by the HA / HAA, it encapsulates it and passes it to the IP address of the COA /
FA, who on receipt, decapsulates and sends the packet to the visiting MH
...


5
...
9 The Internet Protocol Version 6 (IPv6)

IPv6 stands for the Internet Protocol Version 6
...
It does away with
some features of the IPv4 while adding many new features
...
To many scientists, this
by itself is a good reason to consider the IPv6
...

This specification is still evolving and an experimental Research and Development
Tested called 6 -Bone (IPv6 Backbone inspired by the success of the Multicast Backbone
(M-Bone) experiment) exists
...
A wealth of information
about this and related initiatives is available at the project site: http://www
...
net/
...
3
...
1 Major Goals of IPv6 Design
Simplification of the basic protocol was the first goal of the design team
...
Reduction in

the packet processing time at the routers was another primary design goal
...

Providing support for a very large number of addresses was probably the most
immediate goal
...
It remains; however, debatable whether 128-bit was the best choice possible
...
Introducing the
Flow Label and Priority fields made it possible
...
This was made possible by
introducing Authentication Header and Encrypted Security Payload Header
...

5
...
9
...
Irrespective of whether a
LAN interface is Ethernet, Token Ring, FDDI, CDDI or Radio based, this common format
called IEEE EUI-64 Address Format would ensure that worldwide uniqueness could be
guaranteed
...

Significance of these unique addresses is that they are used / to be used as tokens for
assignment of DLL level addresses called Link Local Addresses
...
This is, however, important to note here that for being part of a
network or an internetwork having a specific address format is not a prerequisite as long
as some mapping mechanism exists!
5
...
9
...
3 Address
...

Express it in Hexadecimal Format
...
The resultant address shall be the EUI-64 equivalent of the
original 4b-bit address
...
3
...
4 What about the networks for which no IEEE 802 address is available?
Interestingly, some networks exist (or might exist) for which no manufacturer-provided
unique address is available
...
Random number pick-up scheme is one such scheme that may be

used here
...

In one simple yet workable scheme, if there be ‘N’ hosts in such a network, then each of
these ‘N’ stations may randomly pick up a 64-bit number for itself
...


5
...
9
...
Structure of this header has been
depicted below
...

The 4-bit Version field is used for indication of the protocol version
...
Different flow labels can now be assigned as a result of
this enhancement
...
The payload length uses 16 bits to represent the length of the IPv6
payload
...

The Next Header field is an 8-bit field that contains a standard code representing the
type of the optional extension header or transport protocol header following the Base
Header
...

The Hop Limit is an 8-bit unsigned integer that is decremented by 1 by each node that
forwards the packet
...

Source Address is the128-bit address of the node originating the packet
...

Destination Field represents the final destination if the extension header called the
Routing Header is not present; otherwise, it contains the address of the first intermediate
node through which the packet is necessarily expected to pass on its way to the final
destination
...

As for the choice of the 128 bits long addressing scheme is concerned it was the result
of consensus building efforts between two extreme camps supporting 64-bit addresses
and 256-bit addresses respectively
...


4-bit
Version
Field

8-bit Traffic
Class Field

20-bit Flow Label Field
8-bit Next Header
Field
128-bit Source Address

16-bit Payload Length Field

8-bit Hop Limit Field

128-bit Destination Address
Fig
...
8: The IPv6 Base Header Structure
The IPv6 Addresses can be of three basic types:
• Unicast: (One station sends a packet to another single station / interface
...
)
• Anycast: (A form of packet transfer in which the packet is delivered to the
nearest member of a designated group instead of sending to each group member
individually
...


5
...
9
...
These have been shown below
...
There may be instances where several such headers may
be required to be the part of a single IPv6 packet
...
An IPv6 packet may carry
zero or more extension headers, each of them identified by the Next Header field of the
preceding header:
Hop-by-Hop Extension Header
Routing Header
Destination Options Header
Fragment Header
Authentication Header
Encrypted Security Payload Header
Fig
...
9 The IPv6 Extension Headers

Normally, any node along the route of a packet does not examine extension headers;
until the packet reaches the node (or each of the set of nodes, in the case of multicast)
identified the IPv6 header
...
The extension headers must be
processed strictly in the order of their appearance in the packet
...
the Destination Option Header option may not prove adequate
...
) so that the necessary information could be communicated to all the intermediate
routers, who would not bother to process the Destination Option Header by default
...
Its format is as shown below:
Next Header

Header Extn
...
5
...
The Option Type Header in this
case is set to the code ‘194’
...
It may be interesting to note that for
using the Jumbo Payload option, the Length Field of the IPv6 Base Header is set to
zero
...

Alignment of Jumbo Payload Length (32-bit) field is another point to notice! Length field
is necessarily required to start on a 32-bit boundary; and to make it possible, the Option
Type Field (194) is set to 4n+2 boundary
...
Katz and R
...
The primary purpose of such an option is to alert / notify the intermediate routers
that the packet-in-question does have some substantial information that demands a
careful examination
...

Next Header
Option Data

Header Extn
...
5
...
Length

Option Type = 194

Option Data Length

Jumbo Payload Length
Fig
...
12: The Hop-by-Hop Options Header: As used for Jumbograms
The IPv6 Destination Options Header is identified by the Header Type code ’60’
...
The Header Extension Length field
carries an 8-bit number that represents exactly how many 64-bit words, excluding the
first 64-bit word, do exist in the Destination Option Header
...
Not all options have
an associated action! For instance, non-critical / additional information-based options do
not warrant an action in the event of failure of the destination node in recognizing them
...

As for padding, if there are two options to be specified in the Option Data field, they are
to be separated by null bytes (Pad1s) such that the options are at the two farthest ends
of the Option Data field
...
In case the
number of bytes / octets to be skipped exceeds one, preferably the other padding option
should be used (Pad2)
...


Option Type
(2+1+5) bits

Option Data Length

(and Optional Padding, If needed)

Fig
...
13: Inside the Option Type field of the Destination Options Header
The IPv6 Routing Header plays the same role as the Source Routing Option of the IPv4;
i
...
it contains the list of designated intermediate Router Addresses, which should be
traversed by the packet-in-question (depending upon the loose / strict source routing
option)
...
5
...


Next Header

Header Extn
...
5
...
3
...

As vouched by the respective header structures, the major observations would lead to
the following:
•
•
•
•
•
•
•
•
•
•
•
•
•
•

In the IPv6, the IPv4 Options were replaced by Extension Headers
...

Traffic Class field was introduced in the IPv6 header that supports priority (mainly
for real-time applications)
...

The IPv6 header has Payload Length field in place of the Total Length field of
IPv4
...

The IPv6 has Hop Limit field instead of the Time-To-Live field of the IPv4
...

In contrast to the IPv4, which does not have any explicit provision for aiding
privacy and security, the IPv6 does have built-in provisions for these
requirements
...

Both permit Fragmentation, but the IPv6 format keeps it in an extension header
specifically meant for the job unlike the IPv4 format in which this information was
to be maintained in a fixed field within the IP header
...

The IPv6 header does away with the Header Checksum field of the IPv4
...

In IPv4, there were five address classes (A to C of Network / Host combination
types, D for Multicasting and E reserved for future use)
...
Unlike the IPv4, that permits a two-level
hierarchy of network and host prefixes, the IPv6 proposes to offer multi-level

hierarchy or even multiple hierarchies of prefixes
...

5
...
11 The IPv6 Address Notations:
Unlike IPv4 address notation, in which a 4-part IP address was expressed in Decimal
Number System with a ‘
...

Example: ABCD:CA74:120A:4567:BDEA:FA3B:BB4C:1963
IPv6 also permits Address Abbreviation / Shorthand Notation
...
Similarly, this address can be further abbreviated as:
ABCD:0:120A::BB4C:1963 -- a case of eliminating an all-zero part of the
address
...
This notation is called
the Double Colon notation and has the restriction that it can be used only once within a
single IPv6 address
...

An IPv4 address, by prepending 96 zeros may form a valid IPv6 address
...

Example: ::0A00:0003 may be written as ::10
...
0
...
This involves
using a normal IP address followed by a slash (/) followed by a number that represents
Length of the Prefix
...

Example: The notation A127:0:8:a123::/64 refers to a 64-bit Network Prefix in an
IPv6 environment
...
3
...
However, it is possible to set
this lifetime to infinity, as of now
...

Stateful case: This mode requires use of Address Servers
...
3
...
1 Valid Address-Lifetime
This is often defined as the lifetime as assigned by the Address Server in the Stateful
case; and lifetime as computed on the basis of Address-Prefix Lifetime (contained in the
Router Advertisement Message) in the stateless case
...

5
...
12
...
Such
addresses can be used for the current transaction; however, these cannot be used for
initiating a new connection by the TCP
...
3
...
Theoretically, such systems
(hardware or software) are expected to deliver performance that is comparable to those
requiring manual configuration
...

A major feature of such Plug-and-Play systems, as they are often called, is that they are
capable of discovering required details / parameters pertaining to their operating
environment
...
One of
the initial goals of the IPv6 design was to make it autoconfigurable
...
3
...
1 Associated Factors of Autoconfiguration
There are several issues and factors affecting the autoconfiguration and manual
configuration choices
...


The Road to Stateless Autoconfiguration involves adoption of the Stateless Model,
discovery of the lower level (I
...
at the DLL level) addresses, Address Resolution in case
of non-availability of IEEE 802 Addresses in any given environment, Address
Configuration, periodically flushing and updating configuration table, Neighbour
Discovery and Dynamic Address Allocation
...
In case of the Stateful Mode, it is possible for the network
administrators to switch between autoconfiguration and manual modes
...
3
...
2 Stateless Autoconfiguration
Initialization of IPv6 nodes is the primary concern here
...

Next, they send a Solicitation message to routers (ICMP 133) with Hop Limit
of 255 [Repetitions <=3]
...
Typically, a Source Address Option might include Type, Length and DLL
Address
...

In the process, a Router Advertisement message (ICMP 134) is sent
periodically / in response to the Solicitation message -- whichever takes place
earlier
...
5
...
5
...
3
...
3 The Stateful Autoconfiguration
Stateful Configuration can be of automatic or manual type
...
Both
types of configurations could exist simultaneously in a network / internetwork
...
The following section focuses on such
autoconfiguration in detail
...
It is based
on the traditional Client / Server model
...
e
...
Solicitation messages are sent by
making use of the UDP at the UDP Port 547 of the Servers
...
Servers send their response in
the form of an Advertise Messages either to Clients or their Relay Address depending
upon the information content of the Solicitation Message
...
A Host may receive several
Advertisement Messages, in which case, it chooses a Relay Agent and a Server for
further transactions
...
(All these message formats are shown below
for greater clarity
...

Message-Type
C-bit
A-bit
Reserved bits
Link Local Address of Client (128-bit)
(Optional) Relav Agent’s Address (128-bit)
Fig
...
17 DHCP Solicitation Message Format
Format of the DHCP Advertise Message is shown below
...
5
...

Message-Type

S-bit
C-bit
Reserved
[Optional] Server Address (128-bit)
Agent’s Address (128-bit)
Link Local Address (128-bit)
Configuration Parameters / Extensions

Fig
...
19 DHCP Request Message Format

Transaction ID

Format of the DHCP Reply Message shall be as provided below
...
5
...

Message-Type

D-bit
Reserved
Transaction ID
Agent’s Address (128-bit)
Client’s Link Local Address (128-bit)
(Optional) Client Address (128-bit)
Configuration Parameters / Extensions

Fig
...
21 DHCP Release Message Format
Finally, format of the DHCP Reconfigure Message is as shown in the Fig
...
22
...
5
...
3
...
One way to solve the problem of synchronization is by
assigning a q uality of service (QoS)
...
It is here that the IEEE 802
...
A
LAN is called Isochronous if it operates in real time
...
) The IEEE 802
...
g
...
Clearly, the
isochronous scheme symbolizes a departure from the original Ethernet scheme
...
9a) considers voice as the critical component
...
3 / Ethernet
...


The Isochronous Ethernet is compatible with the common videoconferencing, and videodistribution standards
...
144 Mbps of Isochronous (ISDN) technology
...
This is why it is sometimes called as Integrated
Services Local Area Network, or ISLAN 16-T
...
Isochronous Ethernet
provides ninety six 64-Kbps ISDN B channels over the CAT-3 / CAT-5 cable
...
Yet adequate bandwidth remains available for
the Whiteboard-based shared fora, E- FAX (Group-4), E-mail and Voice-mail etc
...

The Isochronous Ethernet solution is one of the most cost-effective multimedia
networking solutions currently available
...
3 environment, only the following steps are required:
1
...

3
...

Replace the existing Ethernet Adapter cards of the identified Multimedia
systems with Isochronous Ethernet Adapters so as to connect these
systems to the above-referred hub
...

For this purpose, an Attachment Unit Interface (AUI) cable is used to
connect the Isochronous Ethernet hub and existing / older Ethernet hubs
...

An alternative and more cost-effective but propriety solution is offered by the 3Com
...
In the 3Com PACE solution, neither existing Ethernet Adapters
nor the cables need to be replaced
...
The PACE solution concentrates upon the frame delivery timing and priority
aspects
...
Since multimedia applications need
consistent, jitter-free and predictable data delivery, this problem required fixing right in
the beginning
...
PACE employs specifically designed trafficcontrol algorithms for providing predictable delivery delay by flow regulation (and thereby
minimization of jitter) and thereby forcing each Ethernet LAN segment to operate at a
very high efficiency (nearly 98%, as per claims)
...
This propriety prioritization scheme offers two levels of
service: high and low
...
As of now, however, the PACE technology has not been able to actually provide
the QoS guarantee often required for high-quality MMI interactions
...
3
...
e
...
It can also be used to
solve part of the host multi-homing problem
...
At the start of any TCP connection or a UDP
association, one such address can be selected as the home address for the connection
or association
...
It has been suggested that site
multi-homing may be seen as a variation of host multi-homing, assigning as many
addresses to each host as many providers to the site
...
(Christian Huitema
quoted from the IETF mailing archives
...
3
...
There exists a Japanese national programme supporting IPv6 as the
country has pledged itself to achieve the national-wide IPv6-capability by the year 2005
...
In India, Centre for Advanced Software
Technologies (CASTLE): a research wing of the Centre for Software Development of the
Birla Institute of Technology & Science at Pilani (BITS-Pilani), through its early initiative
in form of the “ roject IPv6@BITS” had begun an ambitious IPv6 research and
P
development project in the year 1998
...
BITS operates several international IPv6 tunnels including those
connecting Canada, The Netherlands, Singapore, Korea, China and USA as well as
some inland tunnels to Indian Research & Development organizations
...
As of this writing, this project has already brought numerous firsts to
India in the area of next generation network research and development
...
bits-pilani
...
in) may be consulted for more details and technology
transfer requests
...
The list of
technologies, products, IETF documents, projects and papers produced by this research
initiative is available at this site
...
As of now, several IPv6 interest groups exist and most of
them not only have regular meetings but also have active discussion lists
...
Similarly, in Singapore, National
University of Singapore and the SingAREN have joined the international efforts for
testing and deployment of IPv6
...

In Europe, IPv6 has already received a big boost from practically all quarters including
the European Commission
...
), France (INRIA, IRISA, University of Haute Alsace etc
...
), Denmark (Ericsson), Spain (University Polytechnic
of Madrid, University of Vigo, ConsulIntel, Versaware etc
...
In UK,
several universities, Laboratories and other organizations are contributing to the project
...
Several
applications have been ported to the IPv6 and a few applications have been built with
dual-stack (IPv4 as well as IPv6) support
...
Recently, during the Global IPv6 Summit at Madrid, an
interesting demonstration involving use of IPv6 over IEEE 802
...

In USA, the list of contributing organizations including the best-known companies,
Laboratories and a few universities is quite big and seems to grow forever
...
and almost all mobile communication giants including Nokia
and Ericsson have their research groups on IPv6 and are participating in the 6-Bone
initiative
...
The NSF-supported Internet2 initiative (see http://www
...
edu/) has
some of its members contributing to the IPv6-based research and testing
...
) The IPv6 Forum
(http://www
...
org/) has its presence worldwide and by the way of generating
awareness of the IPv6 and presenting business case for IPv6 to the decision makers
...
Adoption of the IPv6 as the base technology by the 3GPP has been
a major boost for the IPv6 in the mobile world and due to the traditional lead of Europe in
the area of mobile telecommunication / networking, IPv6 has been able to make more
headway in Europe than in the North America which has been a leader in fixed
telecommunication / networking
...
ngn
...
ngni
...

The major hub of IPv6 activities in terms of proposals and drafts for various
improvements, modifications and standards remains the corresponding working groups
at the IETF
...
Of late, a host of potential solutions have been proposed
by individuals as well as working groups in the areas like Quality-of-Service (general
mood at the IETF and elsewhere continues to be skeptical in this matter with several
issues left open by most of the proposed modifications to the RFC 2460 in terms of the
QoS), support for multi-homing for mobility etc
...
In view of this author, the IPv6 is
no longer the Next Generation Internet Protocol; it has quietly arrived and even though it
may be some time before the said outstanding issues may be sorted out, it is clear that
after passing through the Dual-Stack (and other) Migration stages, it is destined to play a
major role in the world of Internetworking: both fixed and mobile
...
4 On the Congestion Control in Interneworks
Congestion Control can be of two types; open loop and closed loop
...

Congestion Metrics may include Average / Mean Queue Length, Average number or
percentage of lost / discarded packets, Number of retransmitted packets those had to
be sent again because of Transmitter’s Time-out and Average / Mean Delay in Packet
Delivery
5
...
1 Congestion Control Strategies:
• Congestion control by regulating admission of Packets / Cells
• Congestion control by regulating traffic based on traffic-type / traffic-rate (packet
rate / cell rate / bit rate etc
...
4
...
1 The Anticipatory Buffer Allocation Scheme:
In this scheme, which is particularly suitable for Virtual Circuit Subnets, congestion can
be effectively controlled / avoided by estimating the optimal buffering needs of the

Switches and allocating this buffer capacity to Virtual Circuits on anticipatory / pro-active
basis
...
This scheme differs from the standard VC establishment scheme in the way
that in the latter no buffer-space allocation is reserved at the Switches by the callrequest packet
...
This scheme may be implemented using many different protocols including the
Sliding Window and Stop-and-Wait protocols
...
However,
for the VCs that may not, at an average, have adequate traffic so as to effectively use a
sizeable chunk of such pre-allocated buffer-space, the economics may not be
favourable
...

A possible variation of this scheme could be, as suggested in the beginning, a dynamic
allocation scheme that is proactive by nature and that, by using some adaptive /
statistical buffering need-determination algorithm, estimates / anticipates the required
buffer size and if available, allocates the VC in question
...
Moreover, this
allocation may be done after the establishment of the VC
...
However, this solution is relatively complex to
implement and has a potential of occasional misfire
...

5
...
1
...
It controls further building
up of congestion just by dropping any further packets reaching the node in question,
entirely arbitrarily, without any learned analysis
...
This scheme requires absolutely
no buffer reservation / advance allocation, in complete contrast to the earlier scheme
...
This too is not an
attractive solution because of obvious potential for creating deadlocks
...
4
...
3 Selective Packet Rejection based Congestion Control Scheme
This scheme is the modified version of the previous congestion control schemes
...
The choice of selective acceptance / rejection is governed by a set of
rules
...

5
...
1
...
Any sender node willing to transmit ‘n’ packets to

a receiving node is first required to capture ‘n’ Tokens / ‘Permit for sending ‘n’ packets’
...
The number of total
Tokens available is usually kept constant; and as result, this scheme ensures a
predictable constant traffic, without any loss of packets
...

5
...
1
...
This scheme uses just that! It makes use of what is termed as
‘Choke Packet’ for indicating to the originator about the congestion and expects it to cut
down its transmission rate by a pre-defined percentage
...
Whenever this threshold value is reached,
the congestion control routine gets fired
...
The original packet itself is tagged / included as
payload (to the generated header with a bit set) so as to help the originator learn so that
it does not generate traffic any further / more than the default cut-down rate thereafter for
a stipulated period of time
...
However, most of them have
potential to generate further network congestion due to a lot of possible choke-packet
traffic
...
This scheme has a special feature of helping in cutting down the
incoming traffic systematically and gradually by informing every intermediate Router
along the way of the Choke Packet
...

5
...
2 Deadlock due to congestion
There exists an extreme effect of failure to timely control of congestion! That’s the
Transmission Deadlock / Lock-up State
...

A well-known solution to such deadlocks was suggested long back by Merlin and
Schwietzer that involved use of a specially constructed directed graph showing Buffers
as nodes and arcs connecting a pair of buffers in the same or adjacent router
...


5
...
The reverse is also the responsibility of this layer
...
5
...


5
...
2 Generic Transport Service Primitives:
A possible set of generic Transport Service Primitives include the following primitives:
•
•
•
•
•
•
•

Create / Identify and Assign / Bind
Listen / Wait
Accept
Connect
Send / Transmit
Receive
Disconnect / Close / Terminate

5
...
3 Generic Transport Service Primitives:
A less flexible set of the Transport Service Primitives may include the following
primitives:

•
•
•
•
•

Listen
Connect
Send
Receive
Disconnect

5
...
4 Transport Service Primitives: The Berkeley Sockets Set for the TCP
In the specific case of the TCP Transport Services, following primitives have been
defined in the standard Berkeley Socket API:
•
•
•
•
•
•
•
•

Socket
Bind
Listen
Accept
Connect
Send
Receive
Close

5
...
5 The Transport Service Access Point (TSAP) and the Network Service Access
Point (NSAP)
In an IP network / internetwork, the NSAP refers to the IP Address of the node
...
Both TSAPs and NSAPs could
be one or more per node / host
...
5
...
5
...
An RFC (RFC 793) by John Postel was
the first description of the TCP as seen today
...
It assumes the underlying IP-subnet as unreliable and therefore takes care of
reliability, flow control and reordering of data units as per requirement and sends data to

the IP Layer in MSS-sized blocks or smaller, after prefixing a TCP header to each such
segment
...
MSS is normally of lesser than or equal to the
size of the MTU (for IPv4: 40, for IPv6: 60 )
...
After the data exchange is over, this connection has to be explicitly
Terminated
...
If the ACK does not arrive within a Timeout period, it retransmits the data and waits for a longer period of time to receive an
ACK
...
(Intermediate
failures are not reported to the Application, however!) The maximum period for such
retransmission-attempts and associated wait-periods for a single data unit, put together,
may be anywhere between 4 Minutes to 10 Minutes, depending upon the TCP
implementation and Stack Configuration
...
RTTs are always more for WANs
than for LANs
...
As it provides each of its Segments a Serial Number, reordering, rejection of
duplicate segments etc
...
It uses Sliding Window Protocol for the
purpose of data transmission / reception / flow-control
...
5
...
1 About the TCP Ports
TCP Ports are 16-bit numbers
...
(RFC 1700 shows a list suggested initially
...
) FTP over TCP uses 21 whereas TFTP over UDP uses 69 for instance
...
For BSD, the Well-Known Ports are: 1 -1023,
Reserved Ports: 1024-5000 and the Unprivileged Server Ports are: 5001-65535
...
5
...
2 The 3-Way Handshake in TCP
TCP requires a Three-Way Handshake for the Connection-Establishment
...
These packets may be SYN-I-SeqNo (C-to-S), SYN-Ini-Seq-No (S-to-C) on which ACK-I+1-Seq-No piggybacks (S-to-C)
and lastly, ACK-Ini+1-Seq-No (C-to-S)
...
It
takes just 1 -byte of Sequence Number Space
...
It takes place using FIN (Final Segment) and associated ACK
...
SYN contains TCP options
of MSS, Sliding Window Scaling (Left-Shifting by 0 to 14 bits allows window-sizes of 64K
to 1 GB) [RFC 1323 by Jacabson et al], Timestamp (for High-speed connections) etc
...
5
...
3 Of the Crashes and Crash Recovery Mechanisms and Strategies applicable
to the TCP/IP Architecture
In any connectionless packet delivery system, including the IP based systems, there is
always a possibility, however small, that a Transport Protocol Data Unit (TPDU) may be
lost on its way to the destination Host’s Transport Layer
...
These are the very mechanisms that may handle Subnet
Crash Recovery, where so possible
...
This is primarily because of the fact that certain amount of data loss
(apart from the connection-loss, in case of Connection-oriented Transport Services) in
the crashed host is bound to create problems in the recovery process
...

Crash-Classification One:
•

Host Crashes
o Client Crashes
o Server Crashes

•

Subnet-Device Crashes
o Router Crashes
o Bridge Crashes
o Repeater Crashes

•

Link Crashes

Crash-Classification Two:
•

Temporary Crashes / Non-Fatal Crashes

•

Permanent / Fatal Crashes

•

Intermittent / Unanticipated Repeated Crashes

5
...
7
...
Three things would
happen in such a situation:

•

Any User / Control Data currently in the local buffer which is yet to be
written to the disk / storage medium shall be lost
...


•

The data under processing at the time of crash, at the local host shall be
lost
...
Let us assume that our protocol
requires that the downloading Client sends an ACK to the sender only after successfully
writing to the disk (in case of a simple Stop-and-Wait protocol)
...
Let us see what could happen
when this host comes back to operation! When, in this case, the Client Host comes
back, it has already lost the transport connection and any data in its memory
...
The first question is that who should maintain such a
record and where? One possibility is to query the Server about the status, but this is a
non-starter given the sheer resource requirements servers shall be forced to have if they
are to retain all such status data even if for a short duration of say five minutes
...
These points suggest that it may be preferable to expect each Client
Host to maintain these records and utilize them in the event of a crash
...
One possibility is that
soon after the Client Host comes back, it seeks to learn about its network status and
thereafter, retrieves its stored records which have an ‘Incomplete so far’ type of tag /
flag
...
Once such a
connection is setup, the Client may inform the Server that it needs the file-download to
resume from a specific point onward (as per the local record) instead of a fresh fullretransmission
...
5
...
5 Server Crash Recovery Strategies:
Just like the cases we considered for Client Host Crash and a possible Recovery, many
possible situations may arise, though very rarely, in which a Server Host crashes during
a operation, say involving download or upload of a large file
...

Clearly, this scheme assumes that the Crash was of very short duration and that various
Host Clients have yet not ‘closed’ their open connections
...
This suggests that both the Client and the Server need to
maintain their respective records for a possible recovery; but still there may be situations
which may be difficult be handled at the TL itself
...

5
...
Types of Application Server Processes include:
Concurrent Server Process: A process that simultaneously provides any set of
predefined services to one or more requesting clients is called a Concurrent
Server Process
...

A process that solicits any specific service from any designated server is called as a
Client Process
...
7 Summary
The TCP/IP is a Network Architecture comprising of four layers namely, Application
Layer, TCP/UDP Layer, IP Layer and Host-to-Network Interface
...
TCP offers connection-oriented
services whereas UDP offers connectionless services
...

IP and ICMP protocols are inseperable in the practical world
...
A Router is an IP-level device whose primary
function is to decide the optimal routes between any two network nodes
...
Although, IPv4 has
served extremely well over the years, some of the recent developments, particularly in
the world of multimedia internetworking, have found themselves in problems to address
which this protocol was not really designed (for the simple reason that in those days
such applications were relatively rare and nobody anticipated such rapid growth and
acceptance of the internetworking technologies)
...
For
instance, lack of support for flow-specification, smaller address-space, option-handling
overheads, lack of adequate security features etc
...
The IPv6 was
designed to do just that!

As you have witnessed throughout the chapter, the new protocol has a very good
potential for cost-effective multimedia internetworking over existing as well as upgraded
infrastructures
...


5
...

2
...

4
...

6
...

8
...

10
...

12
...

14
...

16
...

18
...

20
...

22
...

24
...

26
...
S
...

B
...
Forouzan & C
...
Fegan: TCP/IP Protocol Suite , Second Edition,
Tata-McGraw-Hill Publishing Co
...
, New Delhi, 2002
...
Cisco
...
htm#xtocid2
29276
Cisco staff: Internetworking Case Studies, Cisco Press, 1996
...

D
...
L
...
2-3,
PHI,1994, 1993
...
Comer: Internetworking with TCP / IP, Vol
...

Dave Koiur: IP Multicasting: The Complete Guide to Interactive
Corporate Networks, John Wiley & Sons, New York, 1998
...
McClain (Ed
...

James Kurose & Keith W
...

K
...
K
...
Stevenson :
Internetworking Technologies Handbook, Second Edition, Cisco Press /
Techmedia, 1999
...
Ammann: Managing Dynamic IP Networks, Tata-McGraw-Hill
Publishing Co
...
, New Delhi, 2001
...
2002,
available on-line at: http://www
...
ac
...
html/
RFC 1009 (Requirements for Internet Gateways)
RFC 1009 (Requirements for Internet Gateways)
RFC 1011 (Official IP)
RFC 1042 (IP over IEEE 802
...

28
...

30
...

32
...

34
...

36
...

38
...

40
...

42
...

44
...

46
...


48
...

50
...
Keshav: An Engineering Approach to Computer Networking,
Addison-Wesley, Reading, 1997
...
Quarterman: Practical Internetworking
with TCP / IP and UNIX, Addison-Wesley, Reading, 1993
...
This however, helps the reader to take a look at
the pre-IPv6 days and realize the wisdom of evolution of the IP
...
Black: TCP / IP & Related Protocols, Second Edition, McGrawHill, N
...
, 1995
...
Buchanan: Advanced Data Communication and Networks, Chapman
& Hall, London, 1997
...
Zheng & S
...


5
...


2
...
If this organization frequently requires arranging
Quality Circle meetings involving key people at various levels working at
different locations, travel expenses and associated support expenditure
might prove prohibitively high
...
Given such an
assignment, what shall be your approach towards providing a viable
technology solution to your client?
Study the LAN infrastructure of any medium or large sized commercial
software development organization
...


4
...


6
...


8
...


10
...

12
...


infrastructure to support high quality videoconferencing, can you suggest
a viable approach to selectively and incrementally solve this problem?
Consider the existing IPv4-friendly setup of the Internet
...
)
A university currently uses a combination of Optical Fibre backbone,
Gigabit Ethernet LAN, Fast Ethernet LANs having IP version-6 atop
them
...

What are the weaknesses of the IPv6 specifications with respect to MMI
traffic handling? Could you suggest any innovative and workable solution
to these problems that would not require any immediate change in the
IPv6 specification itself? This solution may use complementary
capabilities and may work atop the IPv6 layer in the Routers or in any
higher layer on the Hosts
...
What are the possible ways of their deployment in
the TCP/IPv4 and TCP/IPv6 WANs?
As of now, the IPv6 Flow-Label specification is incomplete
...
Can you
enlist the QoS parameters that, in your opinion, should be defined by the
Flow Label field? Please justify your response in each case
...
Also see the Appendices A-1 and A-2
...
If this
architecture is to be ported to the IPv6-only WAIs, then shall it require any
changes? If yes, exactly what changes would you suggest to be made
and why? If no changes are to be made, then please explain exactly how
the existing architecture would be able to work over such internetworks?
What is an IPv6 ESP Header and what is its significance with respect to
WANs?
Enumerate any two major advantages of the DHCP (IPv6 version)?
Enumerate any two major issues concerning the use of the DHCP (IPv6
version)?
Suggest a suitable set of Flow Label parameters for an IPv6-based
network configuration that could permit QoS parameters to be taken into
account
...
In this case,
the university had chosen the RIPv6 as its routing protocol
...
If, you were asked to suggest a detailed

14
...

16
...


18
...
You are expected to present a
detailed, step-by-step solution alongwith necessary logic / data to
substantiate your choice(s)
...

ISLAN based networking has its own quota of problems
...

Compare QoS support features of IPv6 technology with those of IPv4
technology
...
Does it replace the RSVP? Explain in brief
...
)
Consider a large MNC organization having over 2048 computers spread
over 12 countries (having one establishment per country) running a
range of operating systems like MS Windows 2000 / XP, Linux 2
...
x,
SCO Unix OpenServer, IBM’s AIX, HP-UX and Sun Solaris etc
...
If these networks are to be
interconnected in a hierarchical manner and you were asked to suggest a
cost-effective internetworking solution with native IPv6 support to this
problem, what design choices you would make and why? Please explicitly
mention all your assumptions and give brief justification in favour of each
of these
...
Diagrams,
where required, are to be provided
...


Chapter-6

The Internetwork Routing Architectures
Interaction Goals
Interaction Goals of this chapter include developing an understanding of the
internals of the major Routing Architecture involving the Internet and large
Intranets from a designer’s perspective
...

At the end of this chapter, you should be able to:
•
•
•
•
•
•

Understand the internals of the major Internet Routing Architectures,
Identify functionalities, design goals and issues related to the Router
Design,
Choose one of the Routing strategies based on system requirements
...

Differentiate between the characteristics and capabilities of Core
and Edge Routers, and
Use an appropriate Routing Architecture for use in soft-real-time
internetwork designs
...


6
...
Design and choice of appropriate Routing Architectures, therefore, are
extremely important for attaining the desired performance from the internetworks
...
Naturally, each category has a set of Routing Architectures
belonging to it
...
This class of
routing is suitable for small networks, has concerns about control-traffic volume, single
point of failure, and delayed adaptation to changes in topology
...
Its availability and performance
are not impressive
...
Due to distributed nature, processing too is distributed and unlike the central
model, it does not tax a single router’s processor(s)
...
2 About Routing Terminology
It shall be in order to be introduced to select terms relevant to Routing, before moving
ahead
...
(All flooding schemes
suffer from this effect, for instance
...


•

Network Layer Data Unit / Packet Die-out: This refers to the state of termination /
death / lifetime expiry of a packet
...


•

Sink Tree: The optimal routes between any number of given Source nodes and a
certain Destination node, as discussed above, invariably form a tree that might
be seen as starting at the Destination node and ending at the Source node
...


•

Routing Directory / Table: This is a table containing computed routes between
various nodes of a subnet
...


•

Packet Routing Problems: Problems in packet routing arise from one or more of
the following areas concerning routing, management and maintenance:
• Loss of packets
• Receipt and circulation of duplicate packets
• Packet Choking / Network Congestion
• Network Cleansing
• Worst-case upper bound problem
• QoS negotiation
• Failure Handling
• Quick Recovery Requirement
• Route Tracing
• Mobility Support
• Tunnelling Support
• Network Management Support

Sr
No

Link-Id

LinkTraffic

LinkSpeed

LinkCapacity

Mean
Delay
on the
Link

Link-Weight

1

AB

12 pps

400 kbps

...



...



...



...
6
...
3 Classification of Routing Architectures
Algorithm-based Routing Architectures may be broadly divided into two classes, namely,
Static Routing Architectures and Dynamic Routing Architectures
...
Thus, these Routing Architectures could be broadly
divided into the following categories, each of which could have optimality requirement:
• Hierarchical Routing
• Directory Routing
• Broadcast Routing
• Multicast Routing
Policy-based Routing Architectures are classified based on policies leading to the
following classes:
• Policy-based QoS Routing Architectures
• Policy-based Security Routing Architectures
• Policy-based Hierarchical Routing Architectures
• Policy-based Session Routing Architectures

6
...

The term shortest path may be interpreted in a variety of ways including:
• path of the least geographical distance
• path of the least congestion
• path of the least number of Hops
• path of the least mean queuing delay
• path of the least propagation / transmission delay
• Any weighted average based metric can be yet another choice for employing this
scheme
...
4
...
W
...
The gist of this
strategy is given below
...
Each node is labeled with the name of the source node and its distance from
the current node
...
e
...
...
6
...
At the start of the algorithm, all nodes are labelled tentatively
...
As the algorithm progresses, the labels may change
...
At any stage, when it becomes clear that the current label represents the
smallest distance / shortest path between a node and the source node, formers
label is marked as a permanent label
...
As the algorithm progresses, more and more nodes acquire permanent labels
...
The algorithm terminates when the destination node gets a permanent label
...
5 Flooding Based Routing
Flooding-based Routing, as the name suggests uses redundant replication of incoming
packets / NLDUs on available outgoing links
...
5
...
Although
under extreme unpredictability, this algorithm demonstrates consistent robustness and
guaranteed delivery as long as at least one path leading to the destination is available, it
is inherently an inefficient algorithm due to the possibility of indefinite circulation of
packets / NLDUs
...
5
...


•

At every intermediate node 'i' examine the incoming queue of packets, take
the packet at the head of the queue and note the packet-id, line on which it
arrived on, its hop count and destination address
...


•

If the count becomes zero, discard / drop the packet and flush the
corresponding entries in the local table
...


•

Examine the incoming queue and if it is non-empty, repeat steps 2 to 5 else
wait until a new packet arrives and then repeat steps 2 to 5
...
5
...
In this scheme, packets are selectively flooded by
the routers in such a way that they move approximately in the right direction (i
...
leading
towards the Destination)
...
6 Flow-based Routing Algorithm
This is yet another Static Routing Algorithm; but unlike the Shortest Path based Routing
Algorithm and the Flooding based Routing Algorithm, which primarily consider the
Subnet Topology alone, it considers Subnet Topology as well as Load (Traffic)
...
In other words, this scheme may not prove to be effective if
the mean inter-node data flow in a given subnet cannot be reliably predicted / estimated
...

Link / Line Capacity Matrix must be known in advance
...

Mean packet-size must be known
...


The scheme makes use of the fact that under the above stated circumstances, for each
of the links, if the link-capacity, average rate of data-flow and topology are known and if
the traffic -matrix and subnet topology is available in advance, then it is possible to:
1
...
Compute the mean (overall) delay in packet-delivery over the given subnet,
3
...

6
...
It is
the original Dynamic Routing Algorithm used in the erstwhile ARPANET
...
Many Routers still use one or other variation of this algorithm
...

• Each Router locally maintains a Routing Table indexed by an entry for every
other Router in the subnet and identification of a preferred neighbour / link
leading to that Router
...
For instance, it may be any one of Physical
Distance, Hops, Delay etc
...
As this
vector contains estimated distances, it is called a Distance Vector
...


2
13
For the given subnet

B
C

5

E

where, the first column indicates Current Estimates and the second
column refers to Identification Symbol for the corresponding
neighbouring Router
...
6
...
The primary drawback of
this algorithm is its vulnerability to the ‘Count-to-Infinity’ problem
...
(Examples include
the Split Horizon, Split Horizon with Poisoned Reverse etc
...
The default behaviour of the original DVR Algorithm about the
requirement for transmitting a vector for each update brings yet another problem:
instability as well as control-traffic overheads
...
) Due these inadequacies, the erstwhile ARPANET that
was using this algorithm until1979, had to switch over to the Link-State Routing
Algorithms discussed in the following section
...
The latter is used in the BGP
...
8 Link-State Routing Algorithm
As the name suggests, in this algorithm (LSA) exchange of the Link-State Packets over
the subnet hold key to facilitating the routing process
...
6
...
The basic idea involves the computation of the Local Routing
Table by each Router on the basis of its own estimates and the similar Link State
Broadcasts received from other routers in the subnet
...


7
5

Link-Cost
0
7
15
12
5

Ag
e

Send
Flags

Next Hop (Router)
A
B
B
E
E

Acknowledgem
ent Flags

Hop Count
1
1
2
2
1

Data

Fig
...
4: Structure of a Link-State Packet, Routing Table and Packet Buffer (at Router A)
In a simple version, following this algorithm, each router:
• Discovers its neighbours and their Network Addresses by sending special
packets called ‘Hello’ packets
...


•
•
•

Immediately applies its recent knowledge to form Link-state packet, which
encapsulate this estimate; and, sends (broadcasts) the packet to all the
discovered routers
...

Immediately forms fresh Link-State Packets (LSPs) and executes link
state broadcast
...
)

In general, fresh link-state packets are built either periodically or upon occurrence of an
event like node-failure / link-failure / addition of a node or link / revival of a failed node or
link
...

In a typical Link-state packet, the first row indicates the Originating Router, the second
row refers to the Sequence Number of the link-state packet, third row shows the Age of
the packet, the fourth and subsequent rows indicate estimated metrics for each of the
neighbouring routers (B and E in this case)
...
Thus, gradually, each Router
in the subnet learns about the rest of the routers
...

Two of the problems associated with this algorithm include the sequence number
problem (including the wrap around problems and router-crash-reboot-reinitialise based
sequence number problems) and the oscillation problem (due to oscillating costs)
...
This
randomisation also avoids the probability of self-synchronization of instances of LSA’s
execution at different routers in a subnet
...
Thus, a variety of techniques / schemes have been suggested in the literature
to handle accidental or malicious corruption of LSPs
...

Examples of some of the well-known implementations of this scheme include the Open
Shortest Path First (OSPF) scheme and the Intermediate System-Intermediate System
(IS-IS) scheme
...
9 Hierarchical Routing Architectures
Any Routing Architecture that may support flat architectural model (i
...
a nonhierarchical architectural model) cannot be scalable as the number of routers in the
internetworks continues to grow beyond a particular value
...
(Routing Table
needs O(n) space for an ‘n’-router subnet
...
(Please refer to Chapter-1 for recapitulation of some related information
...
9
...
The protocol that these gateways used to
communicate within the campus networks was called the In terior Gateway Protocol
...
9
...
Cisco Systems originally
developed the Interior Gateway Routing Protocol (IGRP) in the mid-1980s
...
Its successor, EIGRP, supports VLSM
...
The most commonly used AS-AS routing protocol prior to the advent of the IGRP
was the Routing Information Protocol (RIP)
...
Moreover, most of the
problems discussed in the section describing the DVR, apply to the IGRP as well
...
DUAL guarantees loop-free routing table
generation irrespective of the frequency of changes in the subnet topology
...
In other words, it may be said that in effect, this update that was
caused by a reduction in the cost leading to any Router no loop can be formed
...
9
...
It is important to note here that in an Inter-AS scenario, though the
Edge Routers / Border Routers / Gateways have to cooperate with one-another, the
involved Autonomous Systems may not necessarily have the same degree of trust in
one-another and therefore all Inter-AS Routing Protocols have to provide methods and
means of configuration and enforcement of suitable checks without adding to the
network overhead beyond acceptable limits
...

This is because of certain weaknesses that came to light with the exponential growth of
the Internet over the years
...
9
...
Incidentally, BGP4 also happens to be the first
version that is capable of handling the CIDR and Supernetting
...
(Advantage of this approach is that BGP can relieve itself of
reliability specific concerns
...
(Since, the routing information used by the
BGP consists of a vector of Autonomous System ID Nos
...
Unlike the DVRP, the PVP
does not suffer from the Count-to-Infinity problem) It is primarily used for exchange of
information between autonomous systems
...
10 Issues in Hierarchical Routing Architectures
Primary issues in the design of the Hierarchical Routing Architectures include
determination of the optimal number of levels of routing hierarchies (as discussed b riefly
in Chapter-1), trust-mapping, QoS-mapping, cost-mapping, translation of data between
different interior and exterior routing protocols (the Border Routers face this problem as
they mediate between the interior and exterior routing domains) and choice of
parameters and mechanisms for collaborative network monitoring
...
(Earlier, these positions were held by
the RIP and EGP respectively
...
11 Summary
There are two primary classes of routing strategies: Centralized Routing and Distributed
Routing
...
Problems in packet routing arise from Loss of packets, Receipt and
circulation of duplicate packets, Packet Choking / Network Congestion, Network
Cleansing, Route Tracing, Network Management Support etc
...
Sub-categories include: Packet
Flooding, Random Routing, Shortest Path Routing, Flow-based Routing, Distance
Vector Routing, Link State Routing, Hierarchical Routing, Directory Routing, Broadcast
Routing and Multicast Routing
...

Distance Vector Routing Algorithm (DVR) is also known as the Bellman-Ford or FordFulkerson Routing Algorithm
...
In the DVR, e ach Router locally maintains a Routing Table indexed
by an entry for every other Router in the subnet and identification of a preferred
neighbour / link leading to that Router
...
On receipt of such Vectors from its neigbours, every Router
revises its estimates and updates its local routing table
...


Link-State Routing Algorithm (LSA) exchange of the Link-State Packets over the subnet
hold key to facilitating the routing process
...
In general, fresh link-state packets
are built either periodically or upon occurrence of an event like node-failure / link-failure /
addition of a node or link / revival of a failed node or link
...

The Interior Gateway Routing Protocol (IGRP) is a protocol based the Intra-AS Routing
Architecture
...
This protocol did not support VLSM scheme
...
6
...
2 The Exterior Gateway Routing Protocol (EGRP)
...
Currently, the most well
known Exterior Gateway Routing Protocol is the Border Gateway Protocol Version 4
...


6
...


A
...
Tanenbaum: Computer Networks, Fourth Edition, Prentice-Hall,
Upper Saddle River, 2002
...
B
...
Forouzan & C
...
Fegan: TCP/IP Protocol Suite , Second Edition,
Tata-McGraw-Hill Publishing Co
...
, New Delhi, 2002
...
Cisco staff: Internetwork Design Guide , 1999 available at:
http://www
...
com/univercd/cc/td/doc/cisintwk/idg4/nd2002
...
Cisco staff: Internetworking Case Studies, Cisco Press, 1996
...
Cormac Long: IP Network Design, Osborne-McGraw-Hill, Berkeley, 2001
...
D
...
L
...
2-3,
PHI,1994, 1993
...
D
...
-1, Fourth Edition, Pearson
Education, New Delhi, 2001
...
Dave Koiur: IP Multicasting: The Complete Guide to Interactive
Corporate Networks, John Wiley & Sons, New York, 1998
...
Garry R
...
): Handbook of Networking and Connectivity, AP
Professional,1994
...
James Kurose & Keith W
...


11
...
Downes, Marilee Ford, H
...
Liu, Steve Spanier & T
...

12
...
Ammann: Managing Dynamic IP Networks, Tata-McGraw-Hill
Publishing Co
...
, New Delhi, 2001
...
Rahul Banerjee: Lecture Notes on Computer Networks, Nov
...
bits-pilani
...
in/~rahul/CN/index
...
RFC 1009 (Requirements for Internet Gateways)
15
...
RFC 1124 (Policy Issues in Interconnecting Networks)
17
...
RFC 1147 (FYI: A list of Network Management Tools)
19
...
RFC 1208 (Glossary of Networking Terms)
21
...
RFC 1825 (IP Security Architecture)
23
...
RFC 1827 (IP Encapsulation Security Payload)
25
...
RFC 1971 (IPv6 Address Autoconfiguration)
27
...
RFC 791 (IP version 4)
29
...
S
...

31
...
Quarterman: Practical Internetworking with
TCP / IP and UNIX, Addison-Wesley, Reading, 1993
...
This however, helps the reader to take a look at the
pre-IPv6 days and realize the wisdom of evolution of the IP
...
Uyless D
...
Y
...

33
...
Buchanan: Advanced Data Communication and Networks, Chapman
& Hall, London, 1997
...
Y
...
Akhtar: Networks for Computer Scientists and Engineers,
Oxford University Press, New York, 2001
...
11 Exercises
1
...

2
...
What is the difference between the Distance vector Routing and Path Vector
Routing? Why is there no count-to-infinity problem in the latter case?
4
...

5
...
Why does the Open Shortest Path First Protocol provide a password-based
aurhentication scheme? Who holds this password and how does the scheme
work?
7
...
Why does the BGP make use of TCP’s capabilities?
9
...


Chapter -7

Internetwork Management Architectures
Interaction Goals
Objectives of this chapter are to introduce the fundamental concepts of network and
internetwork management including local as well as remote networks
...

Analyse the correctness of the IMA design approach,
Tell about how to extend an existing IMA design without throwing away
existing set-up; and,
Differentiate between various direct and indirect / hidden design
constraints and their consequences
...


7
...
The primary objective of the Internetwork Management Architecture
(IMA) is therefore to provide a flexible and robust framework using which effective
internetwork management could be ensured
...
Emergence of Network Operations Centres (NOCs) that monitor the global
network status, maintain the health of the network and assist in an early restoration of
the network operations in case of abnormal network behaviour or intermittent network
crash etc
...


It is in this context, that this chapter attempts to briefly introduce you to this increasingly
challenging area of internetwork management
...
7
...


Network
Management
System /
Entity

Network
Management
System /
Entity

Network
Management
System /
Entity

Agent

Agent

Agent

Management
Object

Management
Object

Management
Object

Network
Node-1

Network
Node-2

Network
Node-N

Fig
...
1: Architecture of an Internetwork Management Architecture: Functional
View
Fig
...
2, on the other hand, depicts the Protocol view of the same IMA
...
While the former view is meant to separate
functions that could in effect help in modularising the different component-code design
elements; the latter is meant to separate sets of rules and conventions used in the
interaction of one or more of the entities involved in network operations, administration /
monitoring / control, p
rovisioning / allocation and behavioural / performance analysis
related activities: those, put together, form the complete set of network management
functionalities
...


Application
Protocol

Application
Protocol

Application
Protocol

Network
Management
Protocol

Network
Management
Protocol

Network
Management
Protocol

Transport
Protocol

Transport
Protocol

Transport
Protocol

Network
Protocol

Network
Protocol

Network
Protocol

Fig
...
2: Architecture of an Internetwork Management Architecture: Protocol View
A look at the Table 7
...

Type
1

Problem
Improper Address Management

2

Improper Fault Management

3

Improper Media Management
(partly overlaps with the Type Two
problem)
Improper Power Management
(partly overlaps Type Two problem)
Improper Security Management

4
5

Symptom
Network access failure due to erroneous IP / IPX
/ NL Address binding to the relevant MAC
Address
Node failure (most common cause that includes
the fault in the node processor, memory, fabric or
interface: the last being the commonest cause),
Link Failure, Connection failure preceded by
marked deterioration in network performance
Recurring but intermittent failure that is not due to
fault in the node or breakage in the medium
Access Failure due to unintended configuration
change
Intermittent or frequent intrusions without trace,
Fatal access errors, Prolonged / Repeated data
delivery

Table 7
...
The sole
exception to this rule, in some cases, can be the Type Five problem, support services for
which may be at times provided by a full-fledged security architecture (see Chapter-8)
...
Most of these are built
around a few network / internetwork management standards including:
•
•
•
•
•
•

OSI-CMIP: The Common Management Information Protocol (The OSI
standard for the network management),
IEEE 802
...

SNMP: The Simple Network Management Protocol (meant for the
TCP/IP internetworks like the Internet and proposed at the IETF),
TMN: The Telecommunications Management Network (The ITU-T
standard for the network management),
WBEM: The Web-based Network Management standards,

Out of these, the SNMP is the most common protocol due to its relatively simple and
distributed architecture
...
7
...
The ISO-OSI Network Management Model 10xxx and the ITU
X
...


Network
Management
System Views

Network
Management
Communication
View

Network Management
Functional View

Structure of
Management
Information (SMI) /
Information View
ISO 10165-x

Organizational / System Management View
ISO 10040-x

Fig
...
3: The ISO’s OSI Network Management Reference Model / Framework

7
...
7
...
Fortunately, to make the things simple, all the older versions
have been accommodated in the newer versions of the SNMP
...

SMI Series

MIB Series

Message
Series

PDU
Series

SNMP Series

RFC 1065 (O)
RFC 1066(O)
RFC 1155

RFC 1067(O)
RFC 1098(O)

RFC 1156

RFC 1157 (v1)
RFC 1158(O)
RFC 1212
RFC 1213
RFC 1215
RFC 1442(O)
RFC 1448(O)
RFC 1902 (v2)
RFC 1905 (v2)

RFC 1443(O)
RFC 1449(O)
RFC 1903 (v2)

RFC 1444
RFC 1904 (v2)
RFC 1906 (v2)
RFC 1907 (v2)
RFC 2271 (v3)
RFC 2272
(v3)
RFC 2274
(v3)

RFC
2273
(v3)
RFC
2275
(v3)

Fig
...
4: The IETF Journey of SNMP: SNMPv1, SNMPv2 and SNMPv3

SNMPv1 Manager

SNMPv1 Manager

Authentication

Authentication

Authentication

SNMPv1 Agent

Authentication

SNMPv1 Agent

Authentication

SNMPv1 Manager

Fig
...
5: The SNMP Architecture: Perspective of the SNMPv1
A typical encapsulated SNMP Protocol Data Unit (called as SNMP PDU) comprises of
an Application Header, a Version Identifier, an SNMP Community Descriptor, and the
SNMP Data
...
Its further encapsulation in IP and subsequent
encapsulation in the lower layer PDU are the next two stages following which the
physical layer takes over and at the receiver end the process is reversed as usual
...
This element maintains a database comprising of two sets of data;
one that is static in nature, contains information about the objects and is known as the

Management Information Base (MIB) and the other that is dynamic in nature and
contains the measured values of the objects
...
However, while the SNMP Manager has both of these the MIB and the
dynamic object-value database, the SNMP Agent has just the MIB
...
7
...
7
...

A major initial attempted enhancement in the SNMPv2 was the provision of the security
features that was not included in final specification due to lack of agreement within the
SNMP developer community
...
One major problem in the initial acceptance of the SNMPv2
was its lack of backward compatibility with the SNMPv1
...
It employs an extended Access Control Model known as the View-based
Access Control Model (VACM) that features greater control and flexibility of
configuration
...
7
...
This form of NMS should not be confused with a true Web-based NMS that
necessarily uses the Web-Client and Web-Server combination with the latter having a
built-in Agent meant to monitor, control and thus manage as requested by the WebClient (typically a browser)
...
DMI, SNMP both
were meant to complement each other but in some way have proved to be competitors
...
Sun’s Java Management
Extensions (JMX) is a Java-based framework for making Java Applet-based
management tools as Web-based management extensions with Java-embedding
...
2
...
The SNMP version 3, as shown in the Fig
...
4, has been described in the RFCs 2271-2275
...

A typical view of the SNMPv3, in this case, may depict a multi-node
network/internetwork in each node of which an SNMPv3 entity resides such that
constituents of each SNMPv3 entity (Management Engine and Application Interface) and
their respective attributes assist these nodes in exchange, interpretation, monitoring and
managing the configured network/internetwork, as the case may be
...


Collectively, these four sub-systems form the core/kernel of the SNMPv3 Entity and
known as the SNMPv3 Management Engine often simply called as SNMPv3 Engine
...
An SNMPv3 Engine ID is distinguished from its earlier versions with
the help of the first bit ( in case of v3) of the snmpEngineID
...
An SNMPv3
Entity is named by its unique SNMPv3 Engine ID and there exist two types of names
that are associated with any ID as per the SNMPv3 syntax; namely, principal (the
service requesting user’s or application’s name) and securityName (the pronounceable
string associated with the first name) respectively
...

The SNMP Command Generator is used to generate a variety of single / bulk get (e
...

get-request and get-bulk) as well as set (set request) messages
...
The SNMP Command Responder is used to react to the requests
generated by the SNMP Command Generator application invoked by a remote SNMP
Entity
...
The SNMP Notification Responder /
Receiver first gets an explicit registration at the SNMPv3 Engine and thereafter receives
the alert / notification messages and reacts as defined
...
(In principle, SNMPv3
Proxy Forwarder is functionally the same as the SNMP Proxy Server of the earlier
version
...
(In fact, already some such blocks have been defined
...
The specification also presents the
conceptual abstraction of such an interface that is application independent and offers a
range of general services to the requesting subsystems
...


A major enhancement visible in the SNMPv3 is the provision of Security Management in
SNMP transactions in form of measures for authentication, privacy management,
authorization / access control and flexibility of choice of mutually agreed security
protocols / algorithms
...
During the interaction between two SNMPv3 Engines, at any
given point of time, based on specified governing rules, one acts as an Authoritative
SNMP Engine while the other acts as the Non-Authoritative SNMP Engine
...
3 The Remote Monitoring Protocol
It was the unprecedented success of the SNMP that led to the chain of developments
each building onto the success of its predecessor
...

The basic principle behind the RMON is simple: collect / probe and analyse the network
monitoring information locally and then communicate the extracted information in a predefined format and manner to a remotely located network node functioning as a
designated Network Management Station (NMS)
...

Use of these RMON devices helps in reducing the SNMP-specific traffic overhead in the
WAN-subnet, requires lesser use of active network agents (instead of continuous
visibility requirement of such agents to the network management entities), ensuring
relatively accurate solicitation and interpretation of the results of the monitoring
responses; and, finally, allows effective continuous monitoring of LAN segments
...

The RMON-MIB defines RMON groups
...

7
...
In principle, the network management agents are
typically designed to be small, low resource hungry, efficient, object oriented and robust:
though not necessarily intelligent
...

7
...

Emergence of Network Operations Centres (NOCs) that monitor the global network
status, maintain the health of the network and assist in an early restoration of the
network operations in case of abnormal network behaviour or intermittent network crash
etc
...

OSI-CMIP is the Common Management Information Protocol (The OSI standard for the
network management), JMX is the Java Management Extension, TMN is the
Telecommunications Management Network (the ITU-T standard for the network
management) and WBEM is the Web-based Network Management standards
...
7xx Network Management
Framework are functionally equivalent
...
It can be
seen as a two-part architecture: the SNMP Base Architecture that forms the SNMPv3
Management Engine; and, the SNMP Management Command Interface Architecture
that defines the SNMP-specific applications like Command Handler, Alerter, Forwarder
etc
...
In
the SNMP syntax, snmpEngineID refers to the specific unique identifier associated with
an SNMPv3 Engine
...


The SNMP Command Responder is used to react to the r
equests generated by the
SNMP Command Generator application invoked by a remote SNMP Entity
...

(In principle, SNMPv3 Proxy Forwarder is functionally the same as the SNMP Proxy
Server of the earlier version
...
This chain included the evolution of
remote network operation through the network operations centre, network fault
management methods, network configuration management methods, statistical
parametric measurement methods and eventually the evolution of the full-fledged
specifications for the Remote Network Monitoring (RMON)
...

7
...
Information processing systems - Open Systems
Interconnection Specification of Abstract Syntax
Notation One (ASN
...
International Standard 8824, December 1987
...
J
...
, Schoffstall, M
...
, Simple
Network Management
Protocol, STD 15, RFC 1157, May 1990
...
J
...
, Rose, M
...
, Coexistence between
version 1 and version 2 of the Internet-standard Network Management
Framework, RFC 1452, April 1993
...
J
...
, Rose, M
...
, Manager-to-Manager
Management Information Base, RFC 1451, April 1993
...
J
...
, Rose, M
...
, Structure of
Management Information for version 2 of the Simple Network Management
Protocol (SNMPv2), RFC 1442, April 1993
...
J
...
, Rose, M
...
, Textual Conventions
for version 2 of the Simple
Network Management Protocol (SNMPv2),
RFC 1443, April 1993
...
J
...
, Rose, M
...
, Conformance
Statements for version 2 of the Simple
Network Management Protocol
(SNMPv2), RFC 1444, April 1993
...
J
...
, Rose, M
...
, Management
Information Base for version 2 of the Simple Network Management Protocol
(SNMPv2), RFC 1450, April 1993
...
J
...
, Rose, M
...
, Protocol Operations for
version 2 of the Simple Network
Management Protocol (SNMPv2), RFC
1448, April 1993
...
J
...
, Rose, M
...
, Transport Mappings for
version 2 of the Simple Network
Management Protocol (SNMPv2), RFC
1449, April 1993
...
J
...
Fedor, M
...
Davin:
A Simple Network
Management Protocol (SNMP), RFC 1157, May 1990
...
J
...
, Administrative Model for
version 2 of the
Simple Network Management Protocol (SNMPv2), RFC 1445, April 1993
...
J
...
, Security Protocols for
version 2 of the Simple
Network Management Protocol
(SNMPv2), RFC 1446, April 1993
...
K
...
Rose: Management Information Base for Network
Management of TCP/IP-based internets, RFC 1156, May 1990
...
M
...
, Concise MIB Definitions, RFC 1212, March 1991
...
M
...
, Structure and
Identification of Management
Information for TCP/IP-based internets, RFC 1155, May 1990
...
McCloghrie, K
...
Galvin, Party MIB for version 2
of the Simple
Network Management Protocol (SNMPv2), RFC 1447, April 1993
...
7 Exercises
1
...

2
...
Are these
two frameworks identical? Comment in term of architecture, capabilities and
interoperability
...
It is said that the MIB is not a true dynamic database
...
What are principal features of the SMIv2 and how do they relate to the SMI, if at
all?
5
...
What are the security features available in the SNMPv3 and what are the
associated performance trade-offs, if any?
7
...
Study the
Compaq DMI and compare it with the Microsoft’s CIM-based solution
...

At the end of this chapter, you should be able to:
•
•
•
•
•
•

Identify the basic elements of an Internetwork Security Architecture (ISA),
Tailor any combination of network security services,
Evolve your own ISA as per requirements of a situation
...


The treatment assumes the working knowledge of Computer Networks and some
exposure to Operating Systems and Data Communication areas
...
1 Introduction
Traditionally, the Internet has been popular primarily due to its practically unrestricted
access to the majority of its resources those are so conveniently linked, stored, searched
and retrieved
...
Security considerations assume significance as the
Internet comprises of an extremely large number of networks of individual networks most
of which are managed by different organizations and agencies and use a variety of
protocols, policies and technologies the problem of securing the Internet-based
transactions as well as the problem of connecting private networks / intranets to the
Internet adds another dimension of complexity
...


It may be important to realize that there is no such thing as absolute security or one
hundred percent security as this is simply not possible in any shared resource based
system including the Internet
...

Like all good things in life, Internet Security too comes with a price of its own --- the price
to be paid in terms of need for increased processing resources, need for increased
processing time and resultant delays in data-delivery
...
The very nature of best-effort delivery
framework of the Internet Protocol (IP) does not make the problem any simpler!
Naturally, as the security requirements become more stringent, the network /
internetwork performance further droops and it becomes extremely difficult to strike an
acceptable balance between the security needs, desired performance index and the
targeted cost of service
...

Internet Security Architecture (ICA), in general, and Cryptography, in particular, is
expected to provide Confidentiality, Integrity, Authentication and Non-repudiation
mechanisms
...
A good
example of a broad class in which a very large number of applications warrant all the
provision for all of the four features is the Internet Commerce (briefly explored in the
Chapter-11)
...
2 Security Issues in the Intranets and the Internet
There exist some common issues pertaining to the security of any kind of internetwork
...

Primary issues relevant to the internetwork security include choice of degree of security
and privacy targeted, choice of proper encryption algorithm / encryption protocol, choice
of proper key-length / key-type (public versus private key for instance!), choice of
authentication algorithm / authentication protocol, choice of access control policy, choice
of number of levels / tiers of access-control, choice of form of data-encapsulation etc
...

All of these classes have their corresponding security issues in terms of scope,
economics, effectiveness, detection / tracking mechanism, security metric etc
...


8
...
A message that has its real meaning encoded such that even if it becomes
available to an unintended receiver the receiving node could not extract the hidden
meaning is called encrypted message
...

Mathematically, encryption and decryption may be defined as follows:
If the Original (unencrypted) message is denoted by M original, Encrypted version of
the same message is denoted by M encrypted, Decrypted version of this message is
denoted by M decrypted, Encryption Function is denoted by E and Decryption
Function is denoted by D, then the entire process may be expressed as:
E(Moriginal ) = M encrypted
D(Mencrypted ) = M original
D(Mencrypted)) = D( E(Moriginal ) ) = M original
The process of encoding a message such that its meaning could be securely hidden
from the unauthorized or unintended recipients is called Encryption or Enciphering
...

The real challenge here is in carrying out the entire process of encryption and decryption
in a secure manner (often over interconnected topologies like networks and
internetworks of all types and sizes)
...


The term Cryptology refers to the branch of theoretical computer science or formal
mathematics that deals with the theoretical (essentially mathematical) aspects of both
Cryptography and Cryptanalysis
...
3
...

•

•
•

Cryptographic Algorithms (Hardware / Software / Hybrid encryptions possible in
most cases)
o Asymmetric Cryptographic Algorithms / Public-Key Cryptographic
Algorithms
o Channel Encryption Algorithms
§ Link / Link-to-Link (L2L) Encryption Algorithms
§ End-to-End (E2E) Encryption Algorithms
§ L2L and E2E Combination Encryption Algorithms
o Digital Signature Algorithms
o Key-Agreement Algorithms
o Message Authentication Algorithms
o Symmetric Cryptographic Algorithms / Private-Key Cryptographic
Algorithms
Steganographic Algorithms (Hardware / Software / Hybrid encryptions possible in
most cases)
Internet Security Protocols (Hardware / Software / Hybrid implementations
possible in most cases)
o Level-1 Protocols: Simple / Preliminary
§ Private / Symmetric Key-Exchange-based Internet Security
Protocols
• Key-Distribution Centre-based Protocols
o Encryption Protocols
o Authentication Protocols
§ One-way Function-based Authentication
Protocols
§ Two-way Function-based Authentication
Protocols
o
§ Public / Asymmetric Key-Exchange-based Internet Security
Protocols
• Rivest & Shamir’s Interlock Protocol
• Digital Signature-based Session-Key-Exchange Protocols

•

o

o

o

Public-Key and Signed Message Unicast Protocols
o Encryption Protocols
o Authentication Protocols
• Public-Key and Signed Message Broadcast Protocols
o Encryption Protocols
o Authentication Protocols
Level-2 Protocols: Moderate / Intermediate
• Timestamped variants of Level-1 Protocols (e
...
Surety
Technolgies’ Digital Notary System )
• Subliminal Communication Channel Protocols (e
...

Simmon’s Subliminal Digital Signature Scheme)
• Non-Repudiable / Undeniable Digital Signature Protocols
(Trust-based and Plain variations)
• Proxy (Digital) Signature Protocols (proxying without
sharing signatories private key)
• Group (Digital) Signature Protocols (Trust-based and
simple variations)
• Fail-Stop Digital Signature Protocols (e
...
Pfitzmann &
Waidner’s Fail-Stop Digital Signature Scheme)
• Public-Key Fair Coin Flip Protocol
• Poker Protocols (Anonymous Key Distribution-based and
plain variations)
• One-Way Accumulator Protocols
• ANDOS Protocols (ANDOS stands for All-or-NothingDisclosure-Of-Secrets)
• Key-Escrow Protocols (e
...
NSA’s Escrowed Encryption
Standard Scheme)
Level-3 Protocols: Complex / Advanced
• BZK (Basic Zero-Knowledge Proof) Protocols (Interactive
and Non-Interactive variations)
• PZKP (Parallel Zero-Knowledge Proof) Protocols
• MDP (Minimum-Disclosure Proof) Protocols
• Blind Signature Protocols
• Identity-based Public-Key Cryptographic Protocols
• Contract Signing Protocols (Normal and Simultaneous
Signing variations with / without Arbitrator)
• Simultaneous Oblivious Transfer and Signature Protocols
(e
...
Digitally Certified Mailing Schemes)
Level-4 Protocols: Impenetrable
• Electronic Voting Protocols (EVPs)
o Simple Electronic Voting Protocols

Blind Signatures-based Electronic Voting Protocols
Single-CTF Electronic Voting Protocols (CTF
stands for Central Tabulation Facility)
o Twin-CTF Electronic Voting Protocols
o CTF-Less Electronic Voting Protocols
o Multi-Key Cipher Electronic Voting Protocols
o Receipt-Free Electronic Voting Protocols
Secure Multi-Party Computation Protocols (SMPCPs)
o Conditionally Secure Multi-Party Computation
Protocols
o Unconditionally Secure Multi-Party Computation
Protocols
o Secure Circuit Evaluation-based Multi-Party
Computation Protocols
Secure Anonymous Message Broadcast Protocols
Digital Money Protocols / Digital Cash Protocols (e
...
the
Digital Cash Protocols from the Dutch major: DigiCash)
o One-time Digital Cash Protocols
o Multiple-Use Digital Cash Protocols
o E-Coin Protocols (Fixed amount)
o E-Cheque Protocols (Variable amount)
o Anonymous Multi-Party-Supported Credit Card
Protocols
o Anonymous Multi-Party-Supported Bank Transfer
Protocols
o
o

•

•
•

It is increasingly common to find the combination of Encoding, Encryption and Data /
Storage Compression techniques used in ISAs
...
e
...

8
...
2 Examples of Select Applications based on the Layer-based Classification of
ISAs
As explained earlier, the ISA may involve one or more layer of internetwork protocols
...
The most-effective solution, as usual, remains a
multi-tier ISA employing two or more layers (often three layers in the TCP/IP scenario)
...
The well-known Secure Electronic Transaction (SET) developed jointly by two
major Credit Card businesses, VISA and Master Card, is an example in case
...
3
...
It is, however, interesting to note here that
despite better mechanisms being available, in a sizeable number of real-life applications,
relatively primitive authentication architectures are commonly used
...


8
...

Classically, Firewalls can be used for one or more of the following functions:
•
•
•
•

Security policy implementation
Choice of policy enforcement points
Traffic segmentation
Traffic Isolation

However, Firewalls cannot be used for detecting the internal intrusion originating from
the trusted users operating at trusted network nodes and certain unforeseen penetration
(virus / worm etc)
...
The security cover provided by a Firewall requires that the system to be
protected from external threats as well as from internal leakage should strictly route all
incoming as well as outgoing traffic through the Firewall and the policy enforcement
points be defined unambiguously
...
Firewalls are typically located between the untrusted network /
internetwork and the designated trusted network / internetwork
...


8
...
The term ‘a
certain degree’ has been used here for underlining the very fact that no real-life ISA can
ever prove that it is absolutely secure / impenetrable
...
Therefore, in practice, the researchers and implementers
often try to evolve / deploy an ISA solution that is believed to be reasonably secure in
the sense that for all practical purposes the chosen solution shall provide an acceptably
good quality of protection from external threats and penetrations while retaining the
security overhead to the lowest possible level
...
The list of issues is long and includes issues like levels of protection, local security
policy templates, choice of graded security threats, performance degradation monitoring,
cost factor, delay-factor and location-dependence amongst others
...
6 Summary

Primary issues relevant to the internetwork security include choice of degree of security
and privacy targeted, choice of proper encryption algorithm / encryption protocol, choice
of proper key-length / key-type (public versus private key for instance!), choice of
authentication algorithm / authentication protocol, choice of access control policy, choice
of number of levels / tiers of access-control, choice of form of data-encapsulation etc
...
are various form of access-based security breaches
...
whereas the
Transport-Layer Security Solutions include the SSL Architecture
...
An example of a Hybrid Security
Solution is the SET Architecture advanced by Master Card and Visa
...


8
...
Bruce Schneier: Applied Cryptography, Second Edition, John Wiley &
Sons, New York, 2001
...
C
...
Perlman and M
...

3
...
Chapman and E
...

4
...
Maughan, M
...
Schneider and J
...

5
...
Piper: The Internet IP Security Domain of Interpretation for ISAKMP
RFC 2407, November 1998
...
Grady N
...

7
...
Orman: The OAKLEY Key Determination Protocol, RFC 2412, November
1998
...
Harkins and D
...

9
...
501, 1993
...
ISO/IEC

9594-8,

Information

Technology

-

Open

Systems

Interconnection - The Directory: Authentication Framework, CCITT/ITU
Recommendation X
...

11
...
Bajaj & D
...

12
...
Pistoia, D
...
Reller, D
...
Nagnur and A
...

13
...
Doraswamy: The ESP DES-CBC Cipher Algorithm With
Explicit IV", RFC 2405, November 1998
...
Madson and R
...

15
...
Glenn: The Use of HMAC -SHA-1-96 within ESP and AH ,
RFC 2404, November 1998
...
Mani Subramanian: Network Management: Principles and Practice,
Pearson Education, New Delhi, 2000
...
Microsoft Research: Microsoft’s Guideon Firewall Design, available at the
URL:http://www
...
com/technet/treeview/default
...
asp
...
R
...
Monsour: IP Payload Compression Using LZS, RFC
2395, August 1998
...
R
...
Kent: The NULL Encryption Algorithm and Its Use With
IPsec, RFC 2410, November 1998
...
R
...
Adams: The ESP CBC-Mode Cipher Algorithms, RFC
2451, November 1998
...
R
...


22
...
Thayer and N
...
Glenn: Request for Comments: 2411, IP Security
Document Roadmap, November 1998
...
S
...
Chesvick: Internet Security and Firewalls, Second
Edition, Addison-Wesley, Reading, 1998
...
S
...
Atkinson: IP Authentication Header, RFC 2402, November
1998
...
S
...
Atkinson: IP Encapsulating Security Payload (ESP), RFC
2406, November 1998
...
S
...
Atkinson: Security Architecture for the Internet Protocol,
RFC 2401, November 1998
...
Shacham, R
...
Pereira and M
...

28
...

29
...


8
...
What are the various types of Access Violations that may lead to the possible
attacks, security breaches or information corruption over an Internetwork?
2
...
Compare various Internet Security Architectures in terms of acceptance-rate in
the industry, respective strengths and weaknesses, performance overheads and
consistency
...

At the end of this chapter, you should be able to:
1
...
Identify the basic elements of a VoD system,
3
...
Evolve your own VoD architecture as per requirements of a situation
...


9
...

Incidentally, at the present state of technology, these basic requirements are best
met by the MMI Technology (though it is certainly not the only technology capable of
offering the VoD services)
...


9
...
3 The Video-on-Demand System
In view of the current state of technology, the VoD System may be defined as an
Interactive Multimedia System that allows one or more clients to choose and view
any movie (or a video clip of it) out of a large database of movies
...

Constantly drooping prices of multimedia PCs, digital storage devices and associated
hardware in conjunction with readily available user-friendly software have made the
MMI-based VoD System a technology of choice for the majority of people
...
4 T he VoD Architecture
Primary technique used in MMI-based VoD Systems is the Streaming Technique
...
Unlike the
traditional bursty nature of the normal network / internetwork traffic, the Video
Streaming permits continuous (non-bursty) video-traffic and thereby provides better
performance than the traditional non-streaming variants
...

IPv6 is likely to give this technology a further boost to this technology due its support
for faster processing, flow-specifications and associated flexibilities
...
9
...
5 Basic Issues in VoD Design
There exist twelve basic issues related to the design of a good Video-on-Demand
(over the Net) System
...
6 Constituents of a VoD System
A Video-on-Demand System may be seen as comprising of at least five major
constituent components
...

2
...

4
...


Resource Manager
Meta -Data Manager
Application Enabler
A Multi-Agent System comprising of many Agents including a set of
Service Agents and a Monitoring Agent
Security Manger

Resource
Manager

Security
Manager

Application
Enabler

VoD Client

Network Medium (local / remote)

Video-Server
Cluster

Load Balancer

Meta-Data
Manager
Cluster

Fig
...
2: Constituents of the Improved VoD Architecture
Resource Manager may further be seen as comprising of many sub-modules
including:
•
•
•
•
•

Authentication Module (overlaps the functionality provided by the firstlevel Security Manager)
Network / Internetwork Directory Service Module
File System Module
Database System Module
Streaming Service Module

Meta -data Manager is primarily concerned about keeping track of data on content,
load, location and control matters; and, provides a transparent interface to the other
modules including the Client Module
...
Security Manger
is primarily responsible for a multi-level Authentication, Authorization and Access
Control framework that could allow a reasonable degree of customizability at the
administrator’s end
...
7 Internetworking Aspects of Video-on-Demand Technology
As may be evident from the earlier discu ssion, several aspects of the network-based
on-demand technologies have aspects that assume more prominence while the
delivery is targeted over the Wide-Area Internetworks
...

•
•
•
•
•
•
•
•
•
•
•
•
•
•

Media Server Design Constraints
Server Cluster Design Constraints
Server Location / Content Location Scheme
Bandwidth Optimization Goals
Content Synchronization Strategy
Content Distribution Strategy
Load Balancing Mechanism
Auditing Strategy
Interoperability Constraints
Video-Database Design
Ranges of Allowable Quality-dependent / Media-dependent Compression
Ratio
Client Design Constraints
QoS Assurance
Privacy and Security Requirements

Some of the protocols relevant to the VoD over the Internetworks include Internet
Protocol versions 4 and 6, RSVP: Resource ReserVation Protocol, TCP:
Transmission Control Protocol, UDP: User Datagram Protocol, RTSP: Real-Time
Streaming Protocol, RTCP: Real-Time Control Protocol, RTP: Real-time Transport
Protocol, HTTP: Hyper Text Transfer Protocol
...
Work is going on at the IETF and elsewhere to extend this functionality
to the longer distances without disrupting the normal mobile traffic
...
BITS-Pilani maintains a huge searchable
repository of the relevant documents produced worldwide in the direction of solving
the longstanding QoS problems
...
bitspilani
...
in/~ngni/
...
8 Case Study of the Cisco’s IP/TV Solution
Cisco Corporation has developed a cost-effective IP based VoD technology under
the trade name of Cisco IP/TV
...
The solution, however, is not limited to the LAN
technology alone
...


Cisco’s IP/TV is primarily a Video-on-Demand technology for the IP-based
internetworks
...

One major advantage of the IP/TV is its scalable distributed architecture that offers
acceptably good bandwidth-utilization factor through the use of the IP Multicasting for
scheduled broadcasts
...
It can be used with a variety of communication media, Codecs and packet
/ cell switching systems
...

There exist three basic functional elements / building-blocks in the IP/TV:
1
...

3
...

IP/TV Server is responsible for storage, retrieval and transmittal of the video data /
software / programs
...
Currently, it runs on only Microsoft Windows
95, 98, 2000 and NT Workstation based platforms
...
In addition, it can
capture data from DVDs, VCRs and several other devices and media including the
Satellite Microwave media and 75-Ohm CATV Cables
...

Currently, it requires Microsoft NT based platform (requires certain hardware support
for acceptable performance)
...

IP/TV Viewer, as mentioned earlier, is primarily a client software that provides an
intuitive User Interface, negotiates with the Content Manager and Server as per
requirements, displays a structured ‘availability list’ (of videos), i itiates a videon
content request on behalf of the user, permits the user to choose between live
broadcast, scheduled broadcast and video-on-demand services and displays the
requested video on screen
...

Fig
...
3 shows the Cisco’s IP/TV Architecture
...


IP/TV
Viewer

IP/TV
Content
Manager

Shared Media

IP/TV
Viewer

IP/TV
Server Cluster
Fig
...
3: The CISCO IP/ TV Architecture

9
...
A detailed case study of this
project along with entire design is available in public domain at the project website
that can be reached at the URL: http://www
...
ac
...

The following components have been identified as the three main sub-systems of the
Video on Demand System
...


The Server side, in order to provide reliability is sub-divided into server components
that lead to redundancy in the system
...

"Meta Data" essentially means Data about Data
...
So once a particular presentation is updated in the Meta Data Manager, the
Meta Data Manager updates this information with its current Database
...
The Transport Protocols used for the System include RTSP (Real
Time Streaming Protocol), RTP/RTCP (Real Time Protocol/Real Time Control
Protocol) and RSVP (Resource Reservation Protocol)
...
It acts
as a single point of entry to the entire system
...
Only the control servers do
any change that is to be made to the video servers
...
All in all the control server has the following primary
functions:
•
•

Support for administration and remote access facilities,
Providing Control and Data Access Channel between the Control server and
the Administration modules; and,
• Providing the Control and Data Access Channel between the Control and the
Video Servers
...
It also guarantees continuous playback of a stored video to the client
...
10 Summary
VoD may be defined as a service that could provide the ‘required’ Video Data, at an
acceptable transmission rate, of an acceptable quality and at an affordable price as
per the explicit demand / requirement / need of the client
...

The MMI-based Service-on-on-Demand technologies may include Video-on-Demand
Technologies, Audio-on-Demand Technologies, FAX-on-Demand Technologies,
Game-on-Demand Technologies, News-on-Demand Technologies, Education-onDemand Technologies and Finance -on-Demand Technologies
...


9
...

2
...

4
...

6
...
cisco
...

Rahul Banerjee: Architecture of the BITS-MOS: The BITS Multimedia
Operating System, available at the URL: http://www
...
ac
...
html/
Rahul Banerjee: Design of an Innovative Video-on-Demand System,
available at the URL: http://www
...
ac
...
html/
RFC 1112 (IP Multicasting)
RFC 1889 (RTP)

7
...
12 Exercises
1
...


3
...


5
...

7
...


Design and implement a simple VoD system for your intranet using off-theshelf hardware and custom-built software
...
should be readily supported
...

Compare the Cisco IP/TV technology with any other leading-edge
commercial-strength VoD over IP technology in terms of the following:
• Scalability
• QoS
• Availability
• Compression Strategy
• Channel Utilization Efficiency
• Ease of Use
• Ease of Administration
• Compatibility with respect to popular video formats
• Involved Protocols
• Price -Performance Ratio
...

There exist two basic types of Video-on-Demand Systems for networkoriented deliveries
...
Similarly, there do exist many other
individual factors that affect the design of any IP-based VoD System
...
If this architecture is
to be ported to the IPv6 -only WAIs, then shall it require any changes? If yes,
exactly what changes would you suggest to be made and why? If no
changes are to be made, then please explain exactly
Compare the Cisco’s IP/TV Architecture with the BITS Ichhadrishti VoD
Architecture
...
It can
combine streaming video with the application management features
...

Various architecture s based on ATM, TCP/IP etc
...
Which of these technologies has the potential for being a
cost- effective Internetwork-based Distance Learning Technology given the
ground realities of the country of your residence and why? You may project
it for five years from now
...

At the end of this chapter, you should be able to:
•
•
•
•
•
•
•

Identify the basic elements of a Digital Library system,
Identify common elements of the ADDL and CDDL systems,
Tailor any combination of Digital Library service sets over the
internetwork in a way to balance the load,
Evolve your own Digital Library architecture as per requirements of a
situation
...


The treatment, like the related treatment in Chapter 9, presupposes the working
knowledge of Computer Networks and some exposure to Operating Systems and
Data Communication areas
...
1 Introduction
The term Digital Library is often interpreted in a variety of ways
...

Interestingly, not all Digital Libraries fit into this definition, at least as on today
...
In
fact, some e xperts feel that the term Digital Library is, probably, a misnomer
...


In a way, a Digital Library can be seen as a technology solution involving Digital
Computing Machinery, Multi-Level Storage Mechanism, Distributed Multi-Media
Content and associated Software required to manipulate, extract, interact, emulate,
retrieve , collect, catalogue, customize or find any part of this content and selectively
add / modify any relevant content (if appropriately authorized)
...

10
...


10
...
The US led the move by establishing an early
Digital Library Initiative (DLI) handled as a major component of its national
information infrastructure and setting the pace by designating the National Science
Foundation as the primary funding agency for this purpose
...

UCB, UIUC, UCSB, UC, SU and UM were the early leader thus! Germany, UK,
China, Japan, India , Netherlands and several other countries soon followed the suit,
mostly having their own priorities and model architectures
...
Interestingly, a few commercial organizations like the
IBM Corporation and the Sun Microsystems had also realized the need of the hour
and came up with their own characteristic solutions
...
Another common aspect of each of these project-sites is the effort taken /
being taken by the respective site towards establishing a large-scale / medium-largescale test-bed for their pilot tests and debugging purposes
...

Some of the major efforts / architectures / implementations, which have made a
major contribution towards the Digital Library Technology include the following:
•

The ACM Digital Library Architecture -- developed by the ACM (USA)
...

The BITS DigiLib Architecture – a Digital Library being developed at
the BITS, Pilani (India)
...

The German MeDoc Architecture – being developed at the FRG as
the national initiative
...

The Stanford Digital Library Architecture -- developed at the Stanford
University, Stanford (USA)
...

The UCSB Digital Library Architecture – being developed at the
University of California, Santa Barbara (USA)
...

The University of Chicago Digital Library Architecture – being
developed at the University of Chicago, Chicago (USA)
...


10
...
These factors often lead to a
number of design issues including the following:
•
•
•
•
•
•
•
•
•
•

Extent and type of Interoperability with respect to
content form
Extent and type of Interoperability with respect to
presentation format
Extent and type of Interoperability with respect to
software p latform / support
Interoperability with respect to internetwork
communication technologies
Choice of a Meta Data management strategy
Choice of a Location Transparency mechanism
Choice of Acquisition / Organization / Manipulation
mechanisms
Choice of User-Level Service -set vis-à-vis the User
Authorization and Access status
Choice of Authentication, Security and Protection
policies and mechanisms
Choice of Resource Location and Management
mechanism

10
...
At the heart of every Digital Library remains an excellent
architecture for metadata collection, validation, organization and search support
...
6 Internetworking Aspects of Digital Libraries: Multimedia Object
Handling
Primarily, the Digital Library research concentrates upon Internetwork-based
Distributed Multimedia Information Systems
...

Choice of Asynchronous versus Synchronous services forms a major research
issue, in addition to those mentioned above
...
This lack of a standard has created interoperability problems
between synchronous segments of cooperating Digital Libraries
...


10
...
The term InfoBus is an
abbreviation for the Information Bus
...

Primary content or holding of this Digital Library like that of any other library of its
tribe is the Meta Data
...
the InfoBus aims to provide
certain value-added services like bibliography generation, citation analysis etc
...

It may be worth noting here that the InfoBus architecture is being used as a
component of the Stanford Digital Library Project Test-bed; and is not a mature
design as of this writing
...
Fig
...
1 depicts the principal
components of this framework
...


User-n

Information Processing Service

Proxy

BUS
Proxy
Information
Bus
Service

Information Service

Information
Processing Service

Fig
...
1: The Stanford Digital Library Architecture

In principle, Content of the DL may be of any form: text, audio, video, graphics,
image, and three-dimensional models
...
It is
primarily a user interface model-based architecture to support the Stanford Digital
Library Architecture
...
In addition, it offers seamless service integration and
exhibits support for sharing, reuse and persistence
...
Yet another interesting aspect is the use of CORBA (Common Object
Request Broker Architecture) implemented by Xerox Inter-Language Unification (ILU)
System
...
Current version has been optimized for the Netscape Navigator, although
the other popular browsers like Microsoft Internet Explorer is also supported
...
Here, a workcenter is used to refer to a
location wherein a set of pre-defined operations can be carried out with the aid of
locally available tools
...
Examples of a few DILITE Components include Documents,
Collections, Queries, InfoBus, and User-Representation etc
...
A wealth of publicdomain information on the internal design of this architecture is available at the
project site
...
8 Case Study of the CMU Digital Library Architecture
The CMU Digital Library architecture, like the Stanford initiative, is outcome of a DLIsupported (NSF funded) project
...
This architecture, due to its
relative elegance and scalability is being considered a potential architecture for a
media-rich distributed model based Digital Library Architecture
...

There is likelihood that a consortium of select government funded leading institutes of
technology and management of India would soon adopt this architecture from the
CMU for an ambitious Distance Learning initiative by the consortium
...
informedia
...
cmu
...


10
...
One of these
scholars, Sheshadri Vasan, had an initial proposal of bringing some of the
representative quality-journals in any field of knowledge to a more visible platform via
the Internet such that these journals and their contents co uld have a greater reach
and therefore greater readership ultimately resulting in a chain reaction that could
bring more respect to the journal which in turn would attract greater number of good
researchers for publishing their works / results in these
...
) Fortunately for Vasan, he could muster
the support from some other like minded people then residing mostly in Oxford and
London who took the baton further and discussed the idea with their contacts in
academia and industry both of which showed certain degree of definite interest
...
With the backing of the Oxford
University’s Bodelian Library and support from the OUCS, the Trust approached a
few leading journal publishers, organizations and universities and soon had its
advisory support coming from many continents from Asia and Africa to Europe and
North America
...
The idea appealed

to the group and the JournalServer Virtual Digital Library project gradually took off
...
The project
home page is reachable at the URL: http://www
...
org/ and already over
one hundred journals have committed their support to it
...
Metadata
architecture has been developed and a security framework is under development
...

Unlike all other ADDLs discussed in this chapter, this VDL shall offer only a subset of
a true ADDL functionalities limited to Journals (catalogue, abstract, full-text search
facilities already in place although currently limited to the HTML and PDF versions
only)
...
More details are available at
the project site
...
10 Summary
As per the IITA (apex body of the US-NII) report entitled “The Grand Challenge of
Digital Libraries” the final or ultimate goal is the “deep semantic interoperability - the
ability of a user to access, consistently and coherently, similar (though autonomously
defined and managed) classes of digital objects and services, distributed across
heterogeneous repositories, with federating or mediating software compensating for
site-by-site variations
...
Issues here include the
definition and use of metadata and its capture or computation from objects (both
textual and multimedia), the use of computed descriptions of objects, federation and
integration of heterogeneous repositories with disparate semantics, clustering and
automatic hierarchical organization of information, and algorithms for automatic
rating, ranking, and evaluation of information quality, genre, and other properties
...


10
...


2
...


Bruce Schatz & H
...
org/computer/dli/index
...

Bruce Schatz et al: Building the Interspace, 1996, available at the
URL: http://csl
...
uiuc
...
html
...
28-36
...

5
...

7
...

9
...


11
...


Communications of the ACM, Special Issue on Digital Libraries,
April 1995
...
grainger
...
edu/dli/national
...

DLI Staff: The Digital Library Forum home page, accessible at the
URL: http://www
...
org/
...
Taubes, "Indexing the Internet," Science , Sept
...
1,3541,356
...
Chen, Collaborative Systems: Solving the Vocabulary Problem,
IEEE Computer, May 1994, pp
...

IEEE Internet Computing, Special Issue on Digital Libraries, April
1998
...
stanford
...
html
...
Pool, Turning an Info-Glut into a Library, Science , Oct
...
20-22
...
org/computer/dli/r50022/agencies
...


10
...
Suggest an architectural framework, keeping internetworking as well as
economic aspects in focus, using which , in your opinion, any Corporate
Digital Library should evolve
...
Your scheme should permit private as well as
collaborative business paradigms to co -exist in a cost-effective way
...

2
...

3
...

4
...

5
...
Suggest an architectural framework, keeping internetworking as well as
economic aspects in focus, using which, in your opinion, a multi-campus
university should evolve its Digital Library Architecture
...
Your scheme should permit oncampus, distance learning and collaborative learning paradigms to co-exist in
a cost-effective way
...
Please mention all your assumptions clearly
before proposing your solution
...
The Stanford Digital Library Architecture and the IBM DB2 Digital Library
Architecture represent two possible digital library architectures of ADDL and
CDDL type respectively
...
If you were
to design a DL for your organization, how would you address each of these
internetworking concerns? Support your answer with logic / computation
...


At the end of this chapter, you should be able to:
•
•
•
•
•
•
•
•

Find the common elements of the I-Commerce Systems,
Identify the basic design issues related to an I Com system,
Differentiate between E
-Commerce and -Commerce as well as find
I
their common elements,
Recognize the trade-off between various I-Commerce technologies
and choos e the one most appropriate to your specific requirements,
Tailor any combination of service sets over the internetwork in a way to
ensure secure transactions over the Internet,
Evolve your own I-Com-based business architecture as per
requirements of a situation; and
Analyze the correctness of the secure transaction system design,
Tell about how to extend an existing design without throwing away
existing setup
...


11
...
With the traditional commerce getting along the
Internet-based cousin, this is once again a very clear indication
...

Authenticity of the signed / certified documents and their near-impenetrability are
naturally basic concerns in such cases
...

Predecessors of the Internet Commerce or ‘I-Commerce’, as it is popularly known as,
have been traditional and pre-Internet variant of Electronic Commerce (i
...
preInternet E
-Commerce of the EDI and EFT over telephone company’s voice-grade

and data networks respectively)
...


11
...

It is important to note here that like any other business framework, existence of a
sound revenue model is essential for the long-term success of any business based
on I-Commerce as well
...
It was neglect of this factor in the late
90’s and early 2000 AD that lead to a few phenomenal successes followed by a
virtual collapse of several Dot Com ventures leading to almost two years of global
economic depression that gradually reflected in the slow-down of the non-ICommerce segments as well
...
3 Fundamental Components of Internet Commerce Frameworks
As of now, there exist the following principal instruments of the I commerce System
(mostly, over the Web) that can be used as a set of competing or even
complementary (at times) components of scalable I-Commerce Frameworks:
•
•
•
•
•

Electronic Data Interchange (EDI)
Electronic Funds Transfer (EFT)
Secure Electronic Transactions (SET)
Corporate Digital Library Systems (CDLS)
Secure Electronic Messaging Systems (SEMS)

In the following sections, we would explore the EDI, EFT, SET and SEMS only since
the CDLS basics have been already studied in the Chapter-10
...
4 Electronic Data Interchange (EDI)
Electronic Data Interchange (EDI) is a standard syntax based encoded transmission
scheme that permits unambiguous exchange of information of economic / strategic
relevance between autonomous / independent collaborating agencies / partners
(usually, over the Internet)
...

EDI is a technique and a convention of structured document interchange
...
These considerations include the identification of
entities eligible for the document disclosure, decision about the authentication and
authorization schemes and levels, decision about the timing of disclosure and
definition of the nature and extent of interaction
...
5 The EDI Architecture

The EDI architecture, like most contemporary architectures, is a layered architecture
...
11
...

EDI Semantic Layer
EDI Standard Layer
EDI Transport Layer
EDI Physical Layer

Fig
...
1: The Layered EDI Architecture
The EDI Semantic Layer is the layer that is concerned about application layer
functionality's like description of a business application that must drive the EDI in a
given case, format translations, acknowledgements etc
...
EDIFACT Business Form Standards (UN/ECE) and,
2
...
12 Business Form Standards (US)
...

The EDI Transport Layer is concerned primarily with the exact means / mechanism
that may be appropriate for actual transfer of such business documents
...
Naturally, the layer
utilizes the services that either alone or in combination serve the interest of its higher
layers best
...
6 Electronic Funds Transfer (EFT)
The Electronic Funds Transfers (EFTs) are primarily credit transfers between
collaborating agencies like Banks, Financial Institutions, Credit Card Companies etc
...
Like the EDI, EFT too
might exist with or without the Internet although the latter is more common of the two
...
In India, the ICICI Bank in Mumbai was
one of the earliest such I-Commerce initiative
...


11
...
When a credit card purchase is
placed, the merchant / agency receives an ITU X
...

The ITU X
...
509 Certificate Extension Format contains:
Authority-Key Id
Key Usage
Private-Key Usage Period
Certificate Policies
Subject Alternate Name
Basic Constraints
Issuer’s Alternate Name
Private Extensions

SET Certificates: Broad Categories
•
•
•

Digital Signature Certificates
Key Encryption Certificates
Certificate and Certificate Revocation List Signing Certificates

The Thumbs / Thumbprints in the SET
Making use of certain specified type of data to Hash Functions generates these
...
These Thumbprints are thereafter used to determine exactly which
certificates are to be sent to the sender for successful completion of an on-line
business transaction using the SET
...
It insists that consumers necessarily register their accounts with the issuing
financial institution so it can provide the authentic digital certificate
...
Easy yet secure design
...
8 The SET Architecture
As of now, very few I-Commerce sites have really adopted the SET; the situation is
beginning to change, however
...
Like the IBM-Equifax
initiative and the VeriSign's services, the SET initiative may be seen as an effort to

assure prospective I-Commerce agencies and customers that business over the Net
can be secure and has marked financial benefits
...
9 The X
...
400 (1984
...

The X
...
400 agent software that interacts in an X
...

The X
...
400 agent software that behaves
as if it is a store-and-forward node in an X
...

The X
...
400 Message Transfer Agents
...
400 Message Store: It is an entity that is responsible for temporarily storing
X
...

The X
...
400 setup like UAs, MTAs, MSs etc
...
400
MHS
...
435: This is an ISO standard that specifies details of EDI Message Transmission
over X
...

Double Bagging: Double Bagging is a technique in which an X
...
400 network / internetwork
...

An EDI message comprises of a message header and a message body
...
435, unlike the Double Bagging approach, a special ‘EDI Identifier Field’ is
inserted in the X
...
As can be seen, compared to the former method, this
method offers better performance since duplication of information is not required
...
435 has not received warm response by any standard, it
does have certain useful capabilities and features including:
•

It can reliably exchange / manipulate a wide variety of body parts (in a
single packaging entity)
...
400, not just the EDIspecific functions
...


•
•

11
...
435 is yet not ‘hot’)? Interestingly, it is
the MIME standard that is getting greater attention
...
S-MIME has only made the battle more interesting!
MIME (Multipurpose Internet Mail Extension) is popular because of several reasons
including:
•

Support for several mail formats and a large variety of attachments
(including the Multimedia, Spreadsheet, Word-processing, HTML,
Plain Text, EDI etc
...


•
•

Optional encryption and security is available
...


It is relevant to note here that neither the SMTP nor the plain vanilla MIME offers any
encryption or authentication services
...
MIME-version Header
2
...
MIME-Content-Transfer-Encoding Header
4
...
MIME-Content-Description Header
Like the X
...

MIME User Agent (comprises of a Parser Module and a postparsing Dispatcher Module that also invokes a designated
viewer as may have been configured by the user for viewing
different types of contents / formats)
2
...

MIME Message System
4
...


11
...
It resembles the traditional Credit Cards
...


11
...
EDI-VANs are relatively slow because of the EDI-specific
concerns
...
VANs do prove cost-effective if designed well
...
These
modalities may include:
•
•
•
•
•

encapsulation format, if any,
addressing rules and formats,
encryption rules and formats,
certification and signature formats and trust metrics
message formats
...

Two basic types of encryption policies do exist:
Symmetric Encryption Policy / Secret-Key Cryptography &
Asymmetric Encryption Policy / Public-Key Cryptography

•
•
•

Further, an encryption may be categorized as Strong and Weak Encryption
...

Criteria for Digital Signatures Technology
An acceptable technology must be capable of creating signatures that conform to
requirements:
o
o
o
o

It is unique to the person using it;
It is capable of verification;
It is under the sole control of the person using it;
it is linked to data in such a manner that if the data are changed, the
digital signature is invalidated
...

Asymmetric Cryptosystem: It refers to a computer algorithm or series of algorithms
that utilize two different keys with the following characteristics:
o one key signs a given message;
o one key verifies a given message; and,
o the keys have the property that, knowing one key; it is computationally
infeasible to discover the other key
...
Identifies the certification authority issuing it
...
Names or identifies its subscriber;
3
...
Is digitally signed by the certification authority issuing or amending it&
5
...

Certification Authority: This refers to an entity that issues a certificate, or in the case
of certain certification processes, certifies amendments to an existing certificate
...
The keys have the property that the public key can verify a
digital signature that the private key creates
...

The Signature Dynamics Technology
It is an acceptable technology for use by public entities that uses as the means the
metrics of the shapes, speeds and/or other distinguishing features of a signature as
the person writes it by hand
...
Signature Digest is the resulting bit-string produced when a signature is
tied to a document using Signature Dynamics
...
This
is treated as one method of easy authentication
...

Certificate Expiry: Most of the certificates have their period of legal validity as marked
by the issuing entity / authority, after which it is considered as invalid or expired
...

Certificate Validation: It refers to the verification of the Certificate Chain
...
For instance, before transmission of information,

the SET uses the former whereas after the transmission of information, the latter is
used
...

The Public-Key encryption scheme used by the SET is the Public-Key Cryptography
Standard #7 (PKCS #7) developed by the RSA Data Security company
...

The very reason of using such a combination is due to the Encryption Speed of the
DES and the superior security of the PKCS (commonly called as RSA)
...
13 The I-Commerce Gateways
Each application-service component of the I Commerce may have its own gateway
...
An example of a Service Gateway is an
EDI Gateway
...

Recommending a strategy of solving an I-Commerce oriented problem may often
involve the following steps:
1
...

3
...

5
...


Analyze the company / organization’s profile
Analyze the customer / audience satisfaction data
Suggest an I-commerce Architecture that could provide benefits of the
technology with the least possible financial requirements in phases
Build / evolve a structural design
Carry out simulation studies and if required modify the design
Implement a prototype, if it seems a high-risk venture
...


11
...
e
...
Offshoots of the -Commerce frameworks include
I
Mobile-Commerce (better known as M
-Commerce) and the so-called D-Commerce
...

The EDI architecture apart from the Physical Layer, has three other layers namely,
EDI Transport Layer, EDI Standard Layer and EDI Semantic Layer
...
Digital Signature
Certificates, Key Encryption Certificates, Certificate and Certificate Revocation List
Signing Certificates are the prinicipal certificate types
...
VANs do prove
cost-effective if designed well
...
The keys have the property that
the public key can verify a digital signature that the private key creates
...
The Secret-Key encryption schem e used by
the SET is the Data Encryption Standard (DES) scheme developed by the IBM
Corporation
...


11
...

2
...

4
...
Drew: Using SET for Electronic Commerce , Prentice-Hall PTR,
1998
...
Whinston: Frontiers of Electronic Commerce ,
Addison-Wesley Longman, Inc
...

K
...
Nag: E
-Commerce: The Cutting E
dge of Business, Tata
McGraw-Hill, New Delhi, 1999
...


11
...
Suggest an I-Commerce architectural framework, keeping internetworking as well
as economic aspects in focus, using which, in your opinion, a Digital Library should
evolve
...
Please
mention all your assumptions clearly before proposing your solution
...
Can the Public Key Cryptography system be also used as an electronic signature?
Please justify your answer in brief
...
Compare the provisions of the EDI, SET and EFT in terms of transfer formats,
security-support, support for open standards and primary applications
...
What role can biometric methods play in -Commerce frameworks? Explain with
I
the help of a possible scenario
...

Consequently, this chapter includes a brief revisit of Internet Programming
basics, Linux Network Programming and Application Programming Issues
for the Web
...


12
...
By no means, the treatment given here is either complete or in-depth
since the idea here is just to let you have a feel of several basic issues and aspects
of Internet Programming
...
You need only to know a bit of
Network Programming (knowledge of programming through Sockets and RPC is
enough) and have an elementary knowledge of popular Operating Systems like
Linux, Unix, Windows NT/2000 and Solaris
...
1
...
In C, a protocol
implementation provides a struct sockaddr as the elementary form of a Network
Address
...
h>
struct sockaddr {
unsigned short sa_family;
char sa_data [MAXSOCKADDRDATA]
}
In Linux, sockets are created by the socket() system call
...
Then the socket is initialized by

binding it to a particular protocol and address using the bind() system call
...
h>
int socket (int domain , int type, int protocol);
Here, the parameter domain specifies the PF, parameter type usually specifies
either o f SOCK_STREAM or SOCK_DGRAM and parameter protocol specifies the
protocol to be used (0=> default protocol associated)
...

Next, listen() system call is executed for informing the system that the process is
now ready to allow other processes establish a connection to this socket at the
specified end-point
...
accept () is a blocking call as it blocks until a process requests a
connection
...

#include ...

int accept (int sock, struct sockaddr * addr, int * addrlen);
The select () system call can also be made for determining if any connection request
is currently pending to a socket
...


12
...
2 A Subset of Address Families Used in Linux Environment
Unix / Linux Domain:
TCP/IPv4 Domain
TCP/IPv6 Domain
Novell NetWare Domain:
AppleTalk Domain:

AF_UNIX
AF_INET
AF_INET6
AF_IPX
AF _APPLETALK

12
...
3 A Subset of Protocol Families Used in Linux Environment
Unix / Linux Domain:
TCP/IPv4 Domain
TCP/IPv6 Domain

PF_UNIX
PF_INET
PF_INET6

Novell NetWare Domain:
AppleTalk Domain:

PF_IPX
PF_APPLETALK

12
...
4 Socket Errors (ERRNO VALUES)
The various errors returned by Socket-specific operations may include the following:
ENOTSOCK
EDESTADDRREQ
EPROTOTYPE
ENOPROTOOPT
EPROTONOSUPPORT
ESOCKTNOSUPPORT
EPFNOSUPPORT
EAFNOSUPPORT
ENOTCONN
EHOSTDOWN
EHOSTUNREAD

ETIMEDOUT
ECONNREFUSED
EADDRINUSE
EADDRNOTAVAIL
ENETDOWN
ENETUNREACH
ENETRESET
ECONNABORTED
ECONNRESET
ENOBUFS
EISCONN

12
...
Naturally, world’s first Web Server was set up at the CERN
naturally and was known as info
...
ch
...
Lee writes in a brief recount of events that unfolded over the years: “I wrote in
1990 a program called " WorlDwidEweb", a point and click hypertext editor which ran
on the "NeXT" machine
...
Also available was a "line mode" browser by student Nicola
Pellow, which could be run on almost any computer
...
Between the summers of 1991 and 1994, the load on the
first Web server ("info
...
ch") rose steadily by a factor of 10 every year
...
I was under pressure to define
the future evolution
...
”
The WWW is not the Internet, as sometimes believed by the uninitiated
...
It is primarily a Client /
Server oriented technology which has contributed a lot in the rapid growth of the use
of the Internet
...
Often, the entry page, which has an index to
further hyperlinks to parts of itself or other hyperdocuments, is called a Home Page
...

One of the greatest advantages of the WWW technology is the capability of
accessing and transfer of information across the interconnected computer networks
...


12
...
The URLs may consist of two or more
components depending upon the location of the resource (often a file)
...

Name of the Server / Domain on / in which the resource is
located, like: www
...
ac
...
mit
...
nl,
www
...
org etc
...
html ,
/asdf/erp
...

Filename (as shown above as last part of a path)
...
4 The World Wide Web and File Transfer Protocol (WWW & FTP)
The FTP URL may be expressed in many forms including the following:
ftp:////
or
ftp://:@: ...


12
...
e
...

CGI programs / scripts, unless carefully written may invite Security Problems
...
running on it
...
Steps towards writing a Secure
CGI Script may include:

•
•
•

•

•
•
•

•

Before enabling CGI, it may be ensured that a proper
policy of access and ownership of various server
processes exists
...

For Linux / UNIX systems, choice of associating a unique
GID and UID may help
...
conf file where such configuration information
may reside
...
Also, limiting visibility of the server only to
the files under its own root may add to the security
...

The options in the access file, often called ‘access
...

Another file called ’srm
...
Commenting out one more
lines starting with ’Addtype’ and having ‘text/server-parsedhtml’ may lead to restricting use of SSIs
...


12
...
1 The Common Gateway Interface (CGI) and PERL
‘PERL’ stands for Practical Extraction and Report Language
...

PERL is popular primarily due to its suitability for rapid development, ease of use and
maintenance, efficiency and flexibility
...
PERL 5 provides object-oriented capabilities
...

Traditionally, PERL has been used to query Databases in UNIX environments and
this capability of the language now finds support in many other popular environments
as well
...
5
...
pl

(For embedded scripts, in UNIX / Linux systems, a line like #!/usr/local/bin/perl
may have to be placed at the start of the PERL script
...
pl

A pathname may have to be provided in both of the cases
...
5
...
5
...
5
...
5
...
5
...
5
...
5
...
6 The Server Side Includes: An Example
As explained earlier, although there do exist quite a few situations that benefit by the
SSIs, a careless use of these may give hackers an ample opportunity of attacking
the system
...



...
” -->
…



Response Form from the client

...
ac
...
pl” method=“get”>
pilani
...
in”>

name=“address”

value=“rahul@bits-

…

12
...
7
...
Most programs written today run as a
single thread
...
Multithreaded applications are capable of running many
concurrent threads within a single program
...

In Java, a thread shares the original data area of the parent
...
The
default priority of a thread ( Thread
...

(Thread
...
MAX_PRIORITY is set to 10
...

Daemon threads (service threads) are those threads that normally run at a low
priority and provide a basic service to a program / programs
...
7
...
1 Creating threads
Java provides two ways of creating threads:
implementing an interface and
extending a class
...
In this case, one can only extend or inherit from a single parent class
...
They are
used to design the requirements for a set of classes to implement
...


•
•
•

An interface cannot implement any methods; a class that
implements an interface must implement all methods
defined in that interface
...

Furthermore, an interface cannot be instantiated with the
new operator; for example, Runnable a=new Runnable(); is
not allowed
...
7
...
Like Java, it supports Objects; but
unlike Java that is compiled on the Server prior to its execution Java Script (JS) is
interpreted by the Client
...
Similarly, unlike Java, the JS features Dynamic
Binding
...
)

12
...
2
...
Each frame
appears to act like a separate browser windows, displaying multiple information
sources simultaneously
...
Additionally,
the links in a frame can control what is displayed in other frames or windows
...
In order to maintain compatibility
with the browsers that do not support Frames, there is a NOFRAMES tag pair that
displays alternative pages on the screen of such browsers
...
We can also specify
the size in a fixed number of pixels
...

Several other options are available for frames’ support
...
Each given
object has a parent, whether implicitly or explicitly identified
...

In frames’ world, if we wish to have a link to a previously created page, we may insert
a single line like:
passfr
...
bits-pilani
...
in/~rahul/”;
In JavaScript, it is possible to specify functions to be executed in an event-driven
manner
...
7
...
2 Java Script: A Partial Event List
onChange
when a selection, text, or textarea field is
modified or loses "focus"
onClick
clicked or selected

when a button, checkbox, link, or radio object is

onLoad

when a window or a FRAME is loaded

onMouseOverwhen the mouse is moved over a hyperlink
onSelect

when text in a text or textarea field is selected

onSubmit

when a FORM is submitted

These event handlers are identified as additional parameters to specific HTML tags:
BODY, A HREF, INPUT (all forms), FORM, TEXTAREA, and SELECT
...
7
...
3 The Visual Basic Script and its Position vis -à-vis Java Script
The Visual Basic Script (VBScript), like the Java Script, is embedded within an HTML
script
...

The VB Script has born out of the Microsoft Visual Basic language
...

Unlike the JS, the VB Script is not case-sensitive but like the JS, the Visual Basic
Script too requires the HTML tag