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IP ADDRESSING CONFIGURATION
When assigning IP addresses to interfaces on your device, go to these sections for
information you are interested in:
■ “IP Addressing Overview” on page 121
■ “Configuring IP Addresses” on page 123
■ “Displaying and Maintaining IP Addressing” on page 126
IP Addressing
Overview
This section covers these topics:
■ “IP Address Classes” on page 121
■ “Special Case IP Addresses” on page 122
■ “Subnetting and Masking” on page 122
IP Address Classes IP addressing uses a 32-bit address to identify each host on a network. An
example is 01010000100000001000000010000000 in binary. To make IP
addresses in 32-bit form easier to read, they are written in dotted decimal
notation, each being four octets in length, for example, 10.1.1.1 for the address
just mentioned.
Each IP address breaks down into two parts:
■ Net-id: First several bits of the IP address defining a network, also known as
class bits.
■ Host-id: Identifies a host on a network.
For administration sake, IP addresses are divided into five classes. Which class an IP
address belongs to depends on the first one to four bits of the net-id, as shown in
the following figure (in which the blue parts represent the address class).
Figure 35 IP address classes
0 Net-id Host-id
1 Net-id Host-id0
1
Net-id Host-id
01
1 Multicast address011
1 Reserved111
Class A
07152331
Class B
Class C
Class D
Class E
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