RAD Data comm LRS-24 Table C-1. IP Address Class, Address Class First Byte Address Range

LRS-24Installation and Operation Manual Appendix C SNMP Management

An IP address is logically divided into two main portions:

•Network Portion– assigned by the Internet Assigned Numbers Authority (IANA). There are five IP address classes: A, B, C, D, and E. However, only the classes A, B and C are used for IP addressing. Consult your network manager with respect to the class of IP addresses used on your network.

The network portion of an IP address can be one, two or three bytes long, in accordance with the IP address class. This arrangement is illustrated below:

			IP ADDRESS
	Byte 1	Byte 2		Byte 3	Byte 4
Class A	Network Portion	Host Portion
Class B	Network Portion			Host Portion
Class C	Network Portion				Host Portion

Figure C-1 IP Address

The class of each IP address can be determined from its leftmost byte, in accordance with the chart in Table C-1.

Table C-1. IP Address Class

Address Class	First Byte	Address Range
Class A	0 thru 127	0.H.H.H through 127.H.H.H
Class B	128 thru 191	128.N.H.H through 191.N.H.H
Class C	192 thru 223	192.N.N.H through 223.N.N.H

NBytes that are part of the network portion

HBytes that are part of the host portion

•Host Portion–used to identify an individual host connected to the network. The host identifier is assigned by the using organization, in accordance with its specific needs.

Note The all-zero host identifier is always interpreted as a network identifier, and must not be assigned to an actual host.

Often the host portion is further subdivided into two portions:

Subnet number Used to identify departmental subnetworks. The subnet number follows the network identifier.

Host number Last bits of the IP address.

IP Environment C-5

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