Tuesday, 2 June 2015

EIGRP Route Filtering

Narbik's EIGRP Lab 4 - Route Filtering

There are THREE ways of filtering routes from the EIGRP process

Hop Count

By default EIGRP will discard routes that have a hop count higher than 101, but you can configure a different maximum hop count in the EIGRP process by using:
metric maximum-hops %d
Using this will reject any routes that have a hop count greater than %d

Distribute List

Firstly you define an access list that specifies the route you want to filter, and then under the EIGRP process you use the following command:
distribute-list xxx in f0/0
xxx is the number of the access list. This will filter the route from the table. The access-list is written with the source-address being the advertising neighbor and the destination-address being the route.

Distance

Distance can be used to filter routes or improve routes. Again using an access list to specify the route you want to change, under the eigrp routing process use the following command:
distance %metric a.b.c.d 0.0.0.0 xx
where a.b.c.d is the neighbor, %metric is the Administrative Distance (AD) and xx is the access-list number. By default EIGRP has a AD of 90. This can be changed lower to make the route preferred, or if you change it to 255 it will remove the route from the table!

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