CISCO IOS in a Nutshell

Name

network — router

Synopsis

BGP:

network network-number [mask network-mask]
no network network-number [mask network-mask]

IGRP/EIGRP/RIP:

network network-address
no network network-address

OSPF:

network network-address 
               wildcard-mask area area-id
no network network-address 
               wildcard-mask area area-id

Configures

The network for which the routing process is responsible

Default

None

Description

The network command provides a way to tell the routing process what networks it is responsible for. With IGRP, EIGRP, RIP, and, to a degree, BGP, all you need to do is list the network addresses (one per line) for the routing process. To remove a network from the routing process, use the no form of the command.

In OSPF, the network command requires three parameters: a network-address, a wildcard-mask, and an area-id. You must include the area ID. The wildcard mask specifies the portion of an IP address that isn’t part of the network address; for example, a 24-bit mask subnet would use the wildcard mask 0.0.0.255. An interface can be attached only to a single OSPF area. If the address ranges (i.e., address/mask combinations) of two network commands overlap, the OSPF process takes the first match and ignores the rest.

For BGP, the network address is specified using a subnet mask, not a wildcard mask; for example, an 8-bit subnet would use the subnet mask 255.255.255.0. The mask is optional. If it is omitted, a mask of 255.255.255.0 is assumed.

Example

The following commands define a network for RIP and EIGRP ...