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3Com Switch 8800 Configuration Guide Chapter 11 IP Address Configuration
11-1
Chapter 11 IP Address Configuration
11.1 Introduction to IP Address
11.1.1 IP Address Classification and Representation
An IP address is a 32-bit address allocated to a device that accesses the Internet. It
consists of two fields: net-id field and host-id field. IP addresses are allocated by
Network Information Center (NIC) of American Defense Data Network (DDN). To
manage IP addresses conveniently, IP addresses are classified into five types. See the
following figure.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
0
1 0
1 1 0
1 1 1 0
1 1 1 1 0
net-id
net-id
net-id
Multicast address
Reserved
host-id
host-id
host-id
Class A
Class B
Class C
Class D
Class E
net-id: network ID host-id: Host ID
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
0
1 0
1 1 0
1 1 1 0
1 1 1 1 0
net-id
net-id
net-id
Multicast address
Reserved
host-id
host-id
host-id
Class A
Class B
Class C
Class D
Class E
net-id: network ID host-id: Host ID
Figure 11-1 Five classes of IP address
Here, Class A, Class B and Class C addresses are unicast addresses, while Class D
addresses are multicast ones and class E addresses are reserved for special
applications in future. The first three types are commonly used.
The IP address is in dotted decimal format. Each IP address contains four integers in
dotted decimal notation. Each integer corresponds to one byte, for example,
10.110.50.101.
When using IP addresses, note that some of them are reserved for special uses, and
are seldom used. The IP addresses you can use are listed in the following table.