156Appendix E: Understanding IP and IP addressing

Figure 33 IP addressing: class C

Base_Tel-13

Class C addresses range from 192.0.0.X to 223.255.255.X (standard network mask is 255.255.255.0), therefore, we can have 16384-2 class C networks each with 65536-2 hosts (if no subnets).

32 bits

 

 

 

 

 

 

 

 

110

networkid

 

hostid

 

 

 

 

 

3 bit 21 bits 8 bits

Class C indicator

Field subnet in table IPNETWRK

subnet id

hostid

2 to 6 bits 2 to 6 bits

For any class, the hostid can be split into a subnet id and a hostid depending on custom- er requirements. This helps simplify routing to areas. For class C network, the subnet id can range from 2 to 6 bits.

Note 1: Network ids and host ids which are comprised of all 1’s or all 0’s are 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’ networks (networks that use IP but are not connected to the Internet). Class C networks

have 256 of these special addresses ranging from 192.168.0.0 to 192.168.255.0.

Figure 34 Subnet mask: class C

 

 

 

 

 

CLASS C subnet masks

 

 

Base_Tel-14

 

 

 

 

 

 

 

 

 

IPNETWRK

 

No. subnets

 

No. hosts

 

netmask

 

Netmask in binary format

 

subnet size

 

 

 

 

 

 

 

 

 

 

 

 

 

2

62

255.255.255.192

(11111111.11111111.11111111.11000000)

2

 

 

6

30

255.255.255.224

(11111111.11111111.11111111.11100000)

3

 

 

14

14

255.255.255.240

(11111111.11111111.11111111.11110000)

4

 

 

30

6

255.255.255.248

(11111111.11111111.11111111.11111000)

5

 

 

62

2

255.255.255.252

(11111111.11111111.11111111.11111100)

6

 

 

 

 

 

 

Host/Router

 

 

 

 

DMS

 

 

 

 

 

 

 

 

 

 

 

 

297-8991-910 Standard 03.01 August 1999

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Cabletron Systems DMS-100 manual IP addressing class C