Saturday, 10 January 2009

RIP offset

Using a simple RIP you can set a preferred route out of two or more interfaces, in this example we have two external interface serial0/0 and serial0/1 and one internal interface fastethernet0/0

The IP set up on the interface as follows.
serial0/0 - 172.16.12.1
serial0/1 - 172.16.8.1
fastethernet0/0 - 192.168.0.1

In this example serial0/1 is the faster link and serial0/0 is the slower so we want to set a offset to the serial0/0 so that the preferred link to use is serial0/1

to do this we must first define the traffic we want to offset this is done by using access-list

access-list 1 permit 0.0.0.0
access-list 2 permit 192.168.0.0

now the traffic is defined we need to define the RIP networks and the access lists that are used

router rip
network 172.16.12.0
network 172.16.8.0
network 192.168.0.0
offset-list 1 in 3 serial0/0
offset-list 2 out 3 serial0/0


To better understand the offset here is some of the options that are available

offset-list {access-list-number | access-list-name} {in | out} [interface-type interface-number]

This however is of no use in a fail over if the line protocol is still up.

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