This another method to influence the metric in a routing protocol. The offset-list lets you increase the metric when you send a routing update to your neighbor or when you receive it.
You can use this for RIP or EIGRP, it is not supported for OSPF.
In this example wewill show how we can increase the metric
lo01.1.1.1 lo02.2.2.2
R1 ========R2===========R3 (loopback 3.3.3.3)
R2#sh ip eigrp topo
P 10.10.130.0/24, 1 successors, FD is 2297856
via 192.168.23.3 (2297856/128256), Serial2/1
via 192.168.32.3 (5639936/128256), Ethernet0/1
P 3.3.3.3/32, 1 successors, FD is 2297856 ++++++++++++++
via 192.168.23.3 (2297856/128256), Serial2/1
via 192.168.32.3 (5639936/128256), Ethernet0/1
P 10.1.1.0/30, 2 successors, FD is 2195456
via 192.168.12.1 (2195456/281600), Serial2/0
via 192.168.21.2 (2195456/281600), Serial2/2
P 10.10.10.0/24, 2 successors, FD is 2297856
via 192.168.12.1 (2297856/128256), Serial2/0
via 192.168.21.2 (2297856/128256), Serial2/2
We introduce in router R2 a offset-list to reach 3.3.3.3
R2(config)#ip access-list standard 2
R2(config-std-nacl)#permit host 3.3.3.3
R2(config-std-nacl)#
R2(config-std-nacl)#end
R2#
R2(config)#router eigrp 100
R2(config-router)#off
R2(config-router)#offset-list 1 ?
in Perform offset on incoming updates
out Perform offset on outgoing updates
R2(config-router)#offset-list 1 in 300 se2/1
R2(config-router)#offset-list 1 out 300 se2/1
after
R2(config-router)#do sh ip eigrp topology | b 3.3.3.3
P 3.3.3.3/32, 1 successors, FD is 2298156 _++++++++++++++++++++
via 192.168.23.3 (2298156/128512), Serial2/1
via 192.168.32.3 (5639936/128256), Ethernet0/1
P 10.1.1.0/30, 2 successors, FD is 2195456
via 192.168.12.1 (2195456/281600), Serial2/0
via 192.168.21.2 (2195456/281600), Serial2/2
P 10.10.10.0/24, 2 successors, FD is 2297856
via 192.168.12.1 (2297856/128256), Serial2/0
via 192.168.21.2 (2297856/128256), Serial2/2
P 1.1.1.1/32, 2 successors, FD is 2170112
via 192.168.12.1 (2170112/256256), Serial2/0
via 192.168.21.2 (2170112/256256), Serial2/2
P 10.10.50.0/24, 2 successors, FD is 2297856
via 192.168.12.1 (2297856/128256), Serial2/0
via 192.168.21.2 (2297856/128256), Serial2/2
P 10.10.120.0/24, 1 successors, FD is 2298156
via 192.168.23.3 (2298156/128512), Serial2/1
via 192.168.32.3 (5639936/128256), Ethernet0/1
R2(config-router)#
