Cabletron Systems DMS-100 User Manual

Page 152

152 Appendix E: Understanding IP and IP addressing

297-8991-910 Standard 03.01 August 1999

Figure 29

IP addressing: class A

networkid

hostid

bits

hostid

bits

1 bit

2 to 22 bits

For any class, the hostid can be split into a subnet id and a hostid depending
on customer requirements. This helps simplify routing to areas. For class A

Class A indicator

subnet id

Field subnet in table IPNETWRK

2 to 22 bits

Note 1: Network ids and host ids which are comprised of all 1’s or all 0’s are .

network, the subnet id can range from 2 to 22 bits.

reserved. Therefore, subtract 2 from the subnet id and hostid to get the actual count.

Note 2: There are also special addresses that are reserved for ‘unconnected’

Class A networks have one of these special addresses; namely 10.0.0.0.

Class A addresses range from 1.X.X.X to 127.X.X.X (standard network mask
is 255.0.0.0). Therefore, we can have 127-2 class A networks each with
16,777,216-2 hosts (if no subnets).

networks (networks that use IP but are not connected to the Internet).

Base_Tel-9