Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Network Topologies

1

Networking Topologies
 Topology: Commonly used to discuss the
properties of various types of networks
...


 Networks have shapes, and the shape of a
network determines the way it functions
...


2

Factors affecting the choice of
topology used

 Impact of cable breaks on a network
...

 Flow of messages and which nodes see the
messages
...

 Maximum physical size of the network
...

 The final choice of topology could be either
one or more likely a combination of topologies
that depend upon, need, cost, speed, and
reliability
...


 Physical topology: The layout or actual
appearance of the cabling scheme used on a
network
 If you can see it and touch it, it is physical
...


 If you cannot see it or touch it, it is logical
...


 Similar-looking networks can have
quite different logical topologies

4

Physical Topologies
 All physical topologies are variations
of two fundamental methods of
connecting devices:
 Point-to-point
...


5

Point-to-point Topologies
 Point-to-point (PTP) topology connects two
nodes directly together
...

 A mainframe terminal communicating with a
front-end processor
...


 Two devices monopolize a communication
medium
...

6

Point-to-point Topologies
 Point-to-point links can be
 Simplex
 Half-duplex
 Full duplex

7

Multipoint Topology
 Multipoint topologies link three or more
devices together through a single
communication medium
...

 Multipoint Physical Topologies





Star
Bus
Ring
Hybrid
8

Star Topology
 Has its roots in the mainframe world
...

 Depending on the logical architecture
used, several names are used for the
central point including the following:






Hub
Multipoint Repeater
Concentrator
Multi-Access Unit (MAU)
Switch

9

Star Topology
 In its most basic configuration, cables
radiate from a hub or switch as shown
...


12

Star Topology
 Hierarchical star: It is an extension of
the star topology
...

 These hubs or switches are connected to
each other via a central hub
...



Ring topology

 Each node is connected to the two nearest nodes so the entire
network forms a circle
 One method for passing data on ring networks is token passing

 Active topology

 Each workstation transmits data

14

Bus Topology
 The bus is considered a multipoint
system because all devices tap into
the same backbone cable
...

15

Bus Topologies
 There are two variations of the bus topology
...

 A terminator is connected to the last Tconnector at each end of the network
...

 Examples of Bus topology
 ARCnet, (Token bus)
 Ethernet, (10Base2)

17

Hybrid Physical Topologies
 Hybrid topology

 Complex combination of the simple physical
topologies

 Star-wired ring

 Star-wired topologies use physical layout of a
star in conjunction with token ring-passing data
transmission method

18

Hybrid Physical Topologies
 Star-wired bus
 In a star-wired bus topology, groups of
workstations are star-connected to hubs and
then networked via a single bus

19

Hybrid Physical Topologies
 Daisy-Chained
 A Daisy chain is linked series of devices

20

Hybrid Physical Topologies
 Hierarchical hybrid topology
 Uses layers to separate devices by priority or
function

21

Enterprise-Wide Topologies

A distributed backbone connecting multiple LANs
22

Enterprise-Wide Topologies
 Mesh networks
 Routers are interconnected with other routers,
with at least two pathways connecting each
router

23

Logical Topologies
 Refers to the way in which data are
transmitted between nodes
 Describes the way:
 Data are packaged in frames
 Electrical pulses are sent over network’s
physical media

 Logical topology may also be called
network transport system

24

Comparison of Topologies – Star
Configuration
Star

Strength






Network control is
centralized at one point
Network intelligence is
limited to the central
workstation
Radiating workstations can
use the CPU processing of
the central workstation

Weaknesses










Congestion at the central
workstation can slow
transmissions
Failure of the central
workstation renders the
network useless
...

All workstations have their
own communication media,
which can become expensive
The central workstation has a
physical limitation for the
number of workstations that
can be connected
25

Comparison of Topologies – Bus
Configuration Strength

Weaknesses

Bus













Workstations can
communicate directly with
each other
...

Adding another station
amounts to making another
connection to the bus







The approach is appropriate
to a limited geographical
area
...

Failure of the backbone
renders the network
useless
...


26

Comparison of Topologies – Ring and
Hybrid
Configuration

Strength

Ring









Hybrid





All workstations share the
same communication
medium
...

The cost of a single shared
medium is low
...

Benefits of several
topologies can be combined
...


Weaknesses








Each workstation must pass
on unintended messages
...

Network intelligence must be
distributed
...


27

Comparison of Topologies – Mesh
Configuration

Strength

Mesh







Fast response time
...

Connections determined by
movement of data

Weaknesses






Network intelligence must be
distributed
...

Making connections between
many stations is expensive

---