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Cisco IOS Cookbook, 2nd Edition by Ian Brown, Kevin Dooley

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Filtering Routes with EIGRP

Problem

You want restrict which routes EIGRP propagates through the network.

Solution

You can filter the routes that EIGRP receives on a particular interface (or subinterface) using the distribute-list in command as follows:

Router2#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router2(config)#access-list 34 deny 192.168.30.0
Router2(config)#access-list 34 permit any 
Router2(config)#router eigrp 55
Router2(config-router)#distribute-list 34 in Serial0.1
Router2(config-router)#exit
Router2(config)#end
Router2#

EIGRP also provides a distribute-list out command that allows you to filter the routes that are sent out through a particular interface (or subinterface):

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#access-list 57 permit 172.25.1.0
Router1(config)#access-list 57 deny any 
Router1(config)#router eigrp 55 
Router1(config-router)#distribute-list 57 out Serial0/0.2
Router1(config-router)#exit
Router1(config)#end
Router1#

And, with the gateway keyword, you can apply different filters to different neighbors on the same multiple access network:

Router9#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router9(config)#ip prefix-list ALLOWED-PREFIXES permit 10.0.0.0/8 le 32
Router9(config)#ip prefix-list ALLOWED-PREFIXES deny 0.0.0.0/0 le 32
Router9(config)#ip prefix-list ALLOWED-NEIGHBORS permit 172.18.19.1/32
Router9(config)#ip prefix-list ...

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