Transcript 3_hIPAddresses

HIGHER COMPUTER NETWORKING
What You Should Know About IP Addresses
IP addresses are a key part of the TCP/IP protocol and are
used to address and route packets across networks.
You need to know that:
• They are structured into four octets
• They are divided into four classes: ABCD
• They have limitations
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HIGHER COMPUTER NETWORKING
What You Should Know About IP Addresses
The structure of IP addresses (IPv4)
• IP addresses are divided into 4 X 8-bit numbers (known
as octets)
e.g. 11000000 10101000 00000000 00000001
• This structure is represented as xxx.xxx.xxx.xxx where
each xxx is a number from 0 – 255
• Numbers 0, 127, and 255 are reserved for special
purposes and the remaining 253 numbers in each octet
are available to be assigned to nodes on a network
• 32 bits provides 4, 294, 967, 296 unique possible IP
addresses
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HIGHER COMPUTER NETWORKING
What You Should Know About IP Addresses
The division of IP addresses into four classes
• The International Corporation for Assigned Names and
Numbers (ICANN) assigns three major classes of
addresses: A, B, and C.
• Class D addresses are used for multicast messaging.
Address
class
Address range of
first octet
Number of
networks
Number of
hosts on each
network
A
1 - 126
126
16, 777, 214
B
128 - 191
16, 384
65, 534
C
192 - 223
2, 097, 152
254
D
>=224
N/A
N/A
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HIGHER COMPUTER NETWORKING
What You Should Know About Classes of IP Addresses
Class A
• Owner is assigned an address in the first octet
• Then assigns addresses in the remaining three
• Therefore nearly 224 addresses (16.8 million!) that can be
assigned to nodes within their networks
• Assigned to large corporations and educational institutions
E.g. Apple, IBM, Hewlett Packard
• An example of a Class A address is 124.xxx.xxx.xxx
• Range of addresses: 0.0.0.0 – 127.255.255.255
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HIGHER COMPUTER NETWORKING
What You Should Know About Classes of IP Addresses
Class B
• Owner is assigned an address in the first two octets
• Then assigns addresses in the remaining two
• Therefore nearly 216 addresses (65.5 thousand!) that can
be assigned to nodes within their networks
• Assigned to medium-sized organisations
E.g. Microsoft
• An example of a Class B address is 129.57.xxx.xxx
• Range of addresses = 128.0.0.0 - 191.255.255.255
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HIGHER COMPUTER NETWORKING
What You Should Know About Classes of IP Addresses
Class C
• Owner is assigned an address in the first three octets
• Then assigns addresses in the remaining one
• Therefore nearly 28 addresses (256) that can be assigned
to nodes within their networks
• Assigned to small-sized organisations
E.g. Microsoft
• An example of a Class B address is 198.57.104.xxx
• Range of addresses: 192.0.0.0 – 223.255.255.255
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HIGHER COMPUTER NETWORKING
What You Should Know About Classes of IP Addresses
Class D
• These addresses are not used for networking
• Used for multicast messaging where a single message is
sent to each computer in a group of computers sharing a
single IP address
• An example of a Class D address is 239.xxx.xxx.xxx
• Range of addresses: 224.0.0.0 – 239.255.255.255
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HIGHER COMPUTER NETWORKING
What You Should Know About Classes of IP Addresses
Limitations of IP addresses
• Limited to 232 (4, 294, 967, 296) possible addresses
• Due to growth of networking, particularly with recent
growth of wireless, available IP addresses will run out!
Solution
• Internet Protocol version 6 (IPv6) has been developed.
• IP addresses will be extended to 128 bits
• Therefore range will increase to 0 – 2128
• This means embedded systems such as mobile phones,
ATM machines, retail pos systems can be given IP
addresses as well as computers on networks!
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