Introduction to networking
(Yarnfield)
IP addresses
Objectives
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Define an IP address
Describe IP address classes
Describe network and host portions of an address
Describe what a broadcast address is used for
Describe what private IP addresses are used for
The Internet Protocol
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Every machine MUST have a unique address
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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
To find your IP address type ‘ipconfig’ into a command line
window
The network part of the address
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Is used to route the packet to the correct network
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Once the packet is within the network
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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.
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i.e. 194.66.170 would direct the packet to one part of the
Staffordshire university network
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
Host addresses
Address representation (IP v4)
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An IP address is a 32 bit value
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In theory this gives over 4 billion possible addresses
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An IP address is represented by dotted decimal numbers
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In reality the actual number of available addresses is a lot less than
this
In reality within the network the values are represented by binary
As humans we do not use binary, as these are difficult for us to
remember
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Also it is very easy with a large number sequence to make mistakes
when setting the IP address
Address classes
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Address 127.*.*.* is a reserved address to indicate loop
back
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i.e. communicate with the device sending the request
Address classes
Address classes
Broadcast address
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Is an IP address which is used when communications are
required with ALL of the devices with a certain network
address
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This value is 255 in the host part of the address
Private IP addresses
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A number of IP addresses have been reserved for private
use on local LANS
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If you setup a Microsoft windows network it will default to a class
C private network IP address
Subnets
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Subnets allow for a host part of a host address to indicate
a subnet
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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
Subnet address
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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
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192.5.5.35 255.255.255.224
192.5.5.35/27
You cannot skip bits!
Exercise
1.
2.
3.
4.
5.
What are the two parts that make up an IP address?
What are the five classes of IP address, and which ones
can be commercially used?
For an IPv4 IP address, how many bits are used and
what is the total amount of addresses that can be
derived?
What is the purpose of a subnet?
What will a broadcast IP address actually do?
Summary
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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
Questions...
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...are there any?