Cisco RIP Offset-list Configuration example

Cisco RIP Offset-list Configuration example:

The RIP Offset-list is used for adding metrics for inbound or outbound RIP updates.

Here is the topology for RIP Offset-list configuration example:

We will configure outbound  RIP Offset-list on R2 for route 100.100.100.0/22.This outbound RIP Offset-list is attached for link to R1:

access-list 1 permit 100.100.100.0

router rip

 version 2

 offset-list 1 out 5 FastEthernet0/0

 network 192.168.0.0

 network 192.168.12.0

 network 192.168.24.0

 no auto-summary

R1`s routing table before this configuration:

R1#show ip route rip

     100.0.0.0/22 is subnetted, 1 subnets

R       100.100.100.0 [120/4] via 192.168.13.3, 00:00:25, FastEthernet0/1

                                  [120/4] via 192.168.12.2, 00:00:13, FastEthernet0/0

R    192.168.24.0/24 [120/1] via 192.168.12.2, 00:00:13, FastEthernet0/0

R    192.168.34.0/24 [120/1] via 192.168.13.3, 00:00:25, FastEthernet0/1

     192.168.0.0/32 is subnetted, 4 subnets

R       192.168.0.2 [120/1] via 192.168.12.2, 00:00:13, FastEthernet0/0

R       192.168.0.3 [120/1] via 192.168.13.3, 00:00:25, FastEthernet0/1

R       192.168.0.4 [120/2] via 192.168.13.3, 00:00:25, FastEthernet0/1

                    [120/2] via 192.168.12.2, 00:00:13, FastEthernet0/0

After the configuration:

R1#debug ip rip

RIP protocol debugging is on

*Mar  1 01:28:52.991: RIP: received packet with MD5 authentication

*Mar  1 01:28:52.995: RIP: received v2 update from 192.168.12.2 on FastEthernet0/0

*Mar  1 01:28:52.995:      100.100.100.0/22 via 0.0.0.0 in 9 hops

*Mar  1 01:28:52.995:      192.168.0.2/32 via 0.0.0.0 in 1 hops

*Mar  1 01:28:52.999:      192.168.0.4/32 via 0.0.0.0 in 2 hops

*Mar  1 01:28:52.999:      192.168.24.0/24 via 0.0.0.0 in 1 hops

*Mar  1 01:28:52.999:      192.168.34.0/24 via 0.0.0.0 in 2 hops

R1`s routing table after RIP Offset-list configuration on R2:

R1#show ip route rip

     100.0.0.0/22 is subnetted, 1 subnets

R       100.100.100.0 [120/4] via 192.168.13.3, 00:00:23, FastEthernet0/1

R    192.168.24.0/24 [120/1] via 192.168.12.2, 00:00:12, FastEthernet0/0

R    192.168.34.0/24 [120/1] via 192.168.13.3, 00:00:23, FastEthernet0/1

     192.168.0.0/32 is subnetted, 4 subnets

R       192.168.0.2 [120/1] via 192.168.12.2, 00:00:12, FastEthernet0/0

R       192.168.0.3 [120/1] via 192.168.13.3, 00:00:23, FastEthernet0/1

R       192.168.0.4 [120/2] via 192.168.13.3, 00:00:23, FastEthernet0/1

                    [120/2] via 192.168.12.2, 00:00:12, FastEthernet0/0

If we dont use access-list and use offset-list 0 command it influences all routes:

On R2:

router rip

 version 2

 offset-list 0 out 6 FastEthernet0/0

 network 192.168.0.0

 network 192.168.12.0

 network 192.168.24.0

 no auto-summary

R1#debug ip rip

*Mar  1 01:38:29.923: RIP: received packet with MD5 authentication

*Mar  1 01:38:29.923: RIP: received v2 update from 192.168.12.2 on FastEthernet0/0

*Mar  1 01:38:29.927:      100.100.100.0/22 via 0.0.0.0 in 10 hops

*Mar  1 01:38:29.927:      192.168.0.2/32 via 0.0.0.0 in 7 hops

*Mar  1 01:38:29.931:      192.168.0.4/32 via 0.0.0.0 in 8 hops

*Mar  1 01:38:29.931:      192.168.24.0/24 via 0.0.0.0 in 7 hops

*Mar  1 01:38:29.935:      192.168.34.0/24 via 0.0.0.0 in 8 hops