Introduction to Networking with LANs and WANs

IP addresses

Objectives Be able to define what an IP address is Identify and describe the IP address classes Identify and describe network and host portio

ns of an IP address Describe what a broadcast address is used for Describe what private IP addresses are used f

or

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The Internet Protocol Every machine MUST have a unique address

This is referred to as the IP address This address is used to route packets of

information using TCP/IP to a specific machine The address is made up of two parts: a network

address and a host address

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Activity 11. Start up your PC or laptop and connect it to

the college network.

2. Click on the Start button and in the dialog box at the bottom the Start menu type in cmd

3. At the DOS prompt type cd\

4. Now type in ipconfig and press Enter

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ipconfig results

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The network part of the address Is used to route the packet to the correct network

i.e. 194.66.170 would direct the packet to one part of the Staffordshire university network

Once the packet is within the network The host part of the IP address is important to direct the

packet to actual machine within that network The network address size changes depending on

the size of network in which the host is connected Class A, B, and C

All network addresses are issued by InterNIC (http://www.internic.net/) to ensure that all address attached to the Internet are unique

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Host addresses

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Address representation (IP v4) An IP address is a 32 bit value

In theory this gives over 4 billion possible addresses (232) In reality the actual number of available addresses is a

lot less than this An IP address is represented by dotted decimal

numbers In reality within the network the values are represented

in binary As humans we do not use binary, as these are

difficult for us to remember Also it is very easy with a large number sequence to

make mistakes when setting the IP address

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Address classes

Address 127.*.*.* is a reserved address to indicate loop back i.e. communicate with the device sending the

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Address classes

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Address classes

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Activity 2Look at the following IP addresses. Identify

which class they belong to:

192.168.1.254 64.240.32.28 10.1.27.252 130.254.254.253 127.0.0.1 145.10.10.256 254.100.100.155

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Class C

Class A

Class A

Class B

Reserved

Invalid

Class E

Broadcast address An IP address which is used when

communications are required with ALL of the devices with a certain network address This value is 255 in the host part of the address

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Private IP addresses A number of IP addresses have been reserved

for private use on local LANS If you setup a Microsoft windows network it will

default to a class C private network IP address

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Subnets Subnets allow for a host part of a host address

to indicate a subnet These are smaller local networks within the major

network The advantage is that this allows a packet to be

more tightly direct to a host The disadvantage is valuable host addresses are

used to create a subnet More details about subnets will be given during the

course

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Subnet address Also 32 bits in length Indicates which part of the IP address is the

network, and which part is the host Each class has a default subnet mask Class A - 255.0.0.0 Class B - 255.255.0.0 Class C - 255.255.255.0 Example

192.5.5.35 255.255.255.224 192.5.5.35/27

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Activity 31. What are the two parts that make up an IP address?

Network portion/Host portion

2. What are the five classes of IP address, and which ones can be commercially used?

Classes A, B, C, D, E. A B and C can be used commercially

3. For an IPv4 IP address, how many bits are used and what is the total amount of addresses that can be derived?

32 bits – 4, 294, 967, 296

4. What is the purpose of a subnet? To identify the network portion of an IP address

5. What will a broadcast IP address actually do? Transmit to all devices on a particular network or subnet

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Activity 41. Build the network topology below in the

diagram within the lab

2. Assign 192.168.1.254 to PC0 and 192.168.1.253 to PC1

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Summary IP addresses are used to route packets of data

throughout a network IPv4 uses 32 bits Hierarchical in nature Classes are A, B, C, D and E Classes A, B and C are used commercially Broadcast addresses reach all host machines

on a network

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Questions... ...are there any?

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End!

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