Notesale: Turn your study into money

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Meet the frame
Wednesday, October 21, 2015

11:47 AM

Network Interface card (NIC) is a circuit board that plugs into an individual computer and has a cable
attached that is used to connect it to another device on the network
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Binary is strings of ones and zeros passed from computer to computer
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Data is simply binary code, "on or off"
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Network Models Page 1

The MAC Address
Thursday, October 22, 2015

8:43 AM

A hub acts like a repeater by taking every frame of data it receives and sending it out to every other
connected device with identical binary code
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A computer NIC determines if a frame is meant for itself by looking at the MAC address included in the
frame
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Network Models Page 2

Broadcast vs
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In a broadcast transmission, the receiving NIC will see that the destination MAC address is FF-FF-FF-FFFF-FF and will send the packets to its software
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Broadcasts are very important on a LAN
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Broadcast Domain is when a group of computers can hear the broadcast signal
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Switches
Thursday, October 22, 2015

8:43 AM

A smart device that acts like a hub but maintains a table of known MAC address for each device
connected to it is called a switch
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A switch is smart, it keeps track of the MAC addresses on the network, based on ports
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So when one computer wants to talk to another computer, the router
determines what port to send the data too, based on the MAC address
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Network Models Page 4

Introduction to IP Addressing
Thursday, October 22, 2015

8:43 AM

MAC address cannot handle a lot of computers on a network
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To make a big network work, you have to use logical addressing
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IP address are not fixed like a network card
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IP addresses can be used to determine what network they are in
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The last number (ID) is different
for each computer on a network
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A switch connects to a router, and the router connects to another network
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If a computer wants to talk to another computer on a different network, it has to add a destination IP
address and a source IP address to the frames
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When the computer looks at the IP packet, it determines whether or not it is in its own network
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The router then strips away everything in the frame except for the frame packet
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Network Models Page 5

Packets and Ports
Thursday, October 22, 2015

8:43 AM

When a computer receives a frame of data, it has to determine what to do with it
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Port numbers are unique to individual to applications all over the internet
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In a frame, is a destination port number and a source port number
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The first 1024 port numbers are known as "well known ports"
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But the first
1024 ports are reserved ports, you cannot use them as a return port number
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Data travels in bits and pieces
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TCP a connection oriented conversation between two computers to make sure the data gets to where
its going in whole
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- The Sequence number is when you break data into frames, they are assigned a sequence number
to know how to reassemble
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TCP is the overwhelming protocol we use on the internet
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It is not connection oriented
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It is up to the application to determine it
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Packets have sequence numbers so the network software can reassemble the file correctly
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Network Models Page 6

What is a Model?
Thursday, October 22, 2015

8:43 AM

Models are designed to represent an idea of what's going on
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We use models to represent how networks function
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When dealing with networks, the world of technology uses models to help visualize how networks are
organized and function together
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TCP/IP Model
Thursday, October 22, 2015

8:43 AM

The OSI seven-layer model is 7 distinct functions a network must do
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2
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4
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6
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Physical (what type of cables…)
Data Link (anything that works with a MAC address, NIC, switches)
Network (Logical Addresses, routers)
Transport (Assembly / dissemble)
Session (Connection between two systems, sharing files…)
Presentation (used to be used to convert data into something it can read)
Application (The smarts of what makes it aware)

TCP Model:
1
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Internet
3
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Application

Network Models Page 8

OSI and TCP/IP Model Walkthroughs
Thursday, October 22, 2015

8:43 AM

OSI

TCP

Function

1 - Physical

1 - Network
At this first layer is the NIC, cables, hubs and connections to the outside
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If the MAC address is for the NIC, it continues the process
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It then strips off the Frame check sequence and the MAC address information, and keeps the MAC
information off in memory because it might need to send a frame back
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3 - Network

2 - Internet

Here it deals with IP addresses
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What's left in the frame at this
point is the TCP segment, this is designed and ready for the computer and then to whatever application and
format
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If the data is big and being transported out (Webpages,
movies…), it breaks the data apart into many bits and assigns it a sequence number for reassembly later on
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It
then keeps the complete data and sends it up
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6 - Presentation 4 - Application

Designed to format files for applications
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It looks at the port number and keeps the source
port number and sends the data to the right application
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Converts ones and zeros into the appropriate signal for the medium
being used
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Data Link
Layer

Where MAC addresses are found at, where outbound data is labeled with a MAC address header
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Transport
Layer

Deals with sequencing packets

Session Layer Deals with handling connection between machines
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Network Models Page 9



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