05-18-2012 01:15 AM - edited 03-07-2019 06:46 AM
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.
05-18-2012 06:22 AM
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
05-22-2012 02:43 AM
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?
05-22-2012 02:57 AM
Hello Harmeet,
yes your understanding is correct
Hope to help
Giuseppe
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