Route Filter With Route Map In Eigrp.

[Harmeet Singh]

Hello,

I am Preparing for CCNP and reading Cisco press book (Routing). In EIGRP route filtering by route map concept i read a line written as, "If a clause’s match commands refer to an ACL or prefix list, and the ACL or prefix list matches a route with the deny action, the route is not necessarily filtered. Instead, it just means that route does not match that particular match command and can then be considered by the next route-map clause." I didn't understand the meaning of this line. Please any one explain the meaning of this line with examples.

[Giuseppe Larosa]

Hello Harmeet,

what the book says is that last word is given to route-map clause action.

Example:

access-list 11 permit 10.10.10.0 0.0.0.255

access-list  11 deny 10.10.20.0.0.0.255

route-map example deny 10

match address 11

route-map example 20 permit

With the above configuration the subnet 10.10.10.0/24 matches the permit statement of the ACL in first route-map clause and it is denied, that is is not redistributed or advertised

All other existing subnets are redistributed/advertised including IP subnet 10.10.20.0/24 that is denied by ACL 11 invoked as a match in route-map clause 10. The deny in ACL means only that the subnet is not a match in first route-map clause and processing goes on looking at second route-map clause.

The second route-map clause in this example matches everything  so also 10.10.20.0/24 is permitted.

Hope to help

Giuseppe

[Harmeet Singh]

Thnx Larosa,

I am adding some commands in ur configuration

access-list 12 permit 10.10.20.0 0.0.0.255

route-map example deny 15

match address 12

I think now 10.10.20.0 network will not redistributed. M i right?

[Giuseppe Larosa]

Hello Harmeet,

yes your understanding is correct

Hope to help

Giuseppe