Ip Addressing Overview; Ip Address Classes - 3Com MSR 50 Series Configuration Manual

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IP Addressing
Overview

IP Address Classes

IP A
DDRESSING
When assigning IP addresses to interfaces on your device, go to these sections for
information you are interested in:
"IP Addressing Overview" on page 623
■
"Configuring IP Addresses" on page 625
■
"Configuring IP Unnumbered" on page 628
■
"Displaying and Maintaining IP Addressing" on page 630
■
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 (the blue part identifies the address class).
Figure 185 IP address classes
0 7
Class A 0 Net-id
Class B
1 0 Net-id
Class C
1 1 0
Class D
1 1 1 0
Class E 1 1 1 1
Table 34 describes the address ranges of these five classes. Currently, the first
three classes of IP addresses are used in quantities.
C
ONFIGURATION
15 23
Host-id
Host-id
Net-id Host-id
Multicast address
Reserved
31