Networking

1
Networking

• The TCP-IP Protocol Suite (Part 2)
• Carl Smith National Certificate
• Parts adapted from HNC lectures by Steve Leggett
  2002/03

2
What is IP?

• Developed by the American Defence Department.
• Internet Protocol (IP).
• Addresses both LAN's and WAN's.
• IP information is sent in the form of packets.

3
IP Packet
Source Address
Destination Address
Checksum CRC
Data
4
IP Addressing
IP addresses fall into 3 main categories Class
A, Class B and Class C IP addresses consist of 4
bytes (32 bits) in the form AAA.BBB.CCC.DDD
Every interface should have an IP address.
5
IP Addressing...
144.98.100.1
s0
144.98.200.1
e0
s1
144.98.40.1
t0
144.98.30.1
6
IP Addressing
Class A network - NETWORK.HOST.HOST.HOST 1.0.0.0
through to 126.0.0.0 (16.7 million possible
hosts) Class B network - NETWORK.NETWORK.HOST.HOS
T 128.0.0.0 through to 191.255.0.0 (65,536
possible hosts) Class C network -
NETWORK.NETWORK.NETWORK.HOST 192.0.0.0 through
to 223.255.255.0 (256 possible hosts) Class D
start at 224.0.0.0 are used for multicasting
purposes Class E start at 240.0.0.0 are used
for research purposes
7
IP Address examples
Class A address 10.xxx.xxx.xxx Class B
addresses 147.119.xxx.xxx, 144.98.xxx.xxx Cla
ss C addresses 192.2.101.xxx,
221.190.45.xxx NB The number of usable hosts
is two less than the total number possible
because all zeros or all ones cannot be used.
8
IP Addressing
An address using all zero bits is used to specify
the actual network, whilst an address of all ones
is a broadcast address destined for every user on
the network. Defined by RFC 1918 networks and
addresses 10.0.0.0 through to 10.255.255.255,
172.16.0.0 through to 172.31.255.255 and
192.168.0.0 through to 192.168.255.255 These are
reserved to be used only as internally private
addresses not to connect to the Internet.
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Sub-netting
Segments the network into smaller sub-networks of
the whole network. Manipulates the HOST portion
of the address 144.98.xxx.xxx In IP router
networks each router interface must have a
separate subnet address.
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IP Addressing and Sub-netting
144.98.30.3
144.98.30.1
144.98.30.2
144.98.2.1
144.98.10.2
144.98.20.3
144.98.2.2
144.98.1.1
144.98.20.1
144.98.10.1
144.98.1.2
144.98.20.2
144.98.10.2
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Subnet Masks
IP Subnets are defined by using a subnet mask.
The mask denotes how many bits of the host
portion of the address describe the
subnet 144.98.subnet.host This mask is a 32
bit Internet address with all ones in the network
and subnet portion of the address.
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Subnet Masks
Class 'B' Address
8 bits
8 bits
8 bits
8 bits
NETWORK
SUBNET
HOST
NETWORK
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
144
54
2
98
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0
255
0
255
255
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Subnet Masks
255.255.255.0 8 bits used for the subnet
address and 8 bits for the host address. This
means that the 8 bits in the host portion allows
254 hosts and the 8 bits in the subnet portion
allows 254 subnets. 255.255.255.192 we have
taken two bits of the host portion of the
address and used it for the subnet portion.
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Subnet Masks
8 bits
8 bits
8 bits
8 bits
NETWORK
SUBNET
HOST
NETWORK
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
128 64 32 16 8 4 2 1
0 1 1 0 0 0 1 0
1 0 1 0 0 0 0 0
0 0 1 1 0 1 1 0
0 0 0 0 0 0 1 1
144
54
2
98
Class 'B' Address
15
Summary