3Com WX3000 IP Addressing Configuration, IP Addressing Overview, IP Address Classes, Net-id

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The term switch used throughout this document refers to a switching device in a generic sense or the switching engine of the WX3000 series.

The sample output information in this manual was created on the WX3024. The output information on your device may vary.

1 IP Addressing Configuration

IP Addressing Overview

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:

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Net ID: The 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, as shown in the following figure (in which the blue parts represent the address class).

Figure 1-1IP address classes

	0					7	15	23	31
Class A		0		Net-id				Host-id
Class B
		1	0			Net-id		Host-id
Class C		1	1	0			Net-id		Host-id
Class D
		1	1	1	0		Multicast address
Class E		1	1	1	1		Reserved

Table 1-1 describes the address ranges of these five classes. Currently, the first three classes of IP addresses are used in quantity.

1-1