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update issue on broadcast media

Unanswered Question
Nov 28th, 2006
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hi i have 3 routers connected to a switch n only vlan 1 is to used. RA , RB , RC are 3 routers. i m running rip ( u can take igrp, eigrp but not ospf or isis) RA have 2 networks i.e 10.0.0.0/8 and 20.0.0.0/8. my task is that i want RA to only advertise network 10.0.0.0 to RB and 20.0.0.0 to RC only means RB will not get 20.0.0.0 and RC will not get 10.0.0.0 . all configuration is to be done on RA only. the only configuration u can do on RB n RC is to use the neighbour command under config-router mode. apart from that no other configuration is allowed on RB n RC. can any1 help me with it ?? is this task possible plz tell me

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Overall Rating: 4 (1 ratings)
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shahidrox Wed, 11/29/2006 - 10:48
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thanks for the response but i have already tried it, u see i want to filter updates for a SPECIFIC neighbour on a medium where other routers are also getting the updates, how can i prevent it ??? how can i do it ???

sourabhagarwal Tue, 11/28/2006 - 22:02
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  • Gold, 750 points or more

config on RA will look like this to achieve what you want.


access-list 10 permit 10.0.0.0 0.255.255.255

access-list 20 permit 20.0.0.0 0.255.255.255


router eigrp 1

network 10.0.0.0

network 20.0.0..0

distribute-list 10 out s0/0

distribute-list 20 out s0/1

no auto-summary


assuming RA S0/0 is connected to RB and RA S0/1 is connected to RC


rate if it helps or let us know if you have any questions.

tdrais Wed, 11/29/2006 - 11:28
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  • Blue, 1500 points or more

This sounds like one of those trick questions they like to put on the ccie practice labs.


Your issue is that rip is sent by broadcast and the other routers can see and use all the routes.


They gave you the big clue in that you can configure rip neighbors. If you use the neighbor statement it send the updates to the neighbor by unicast.


This still does not prevent it from also sending broadcast. You must set the interface to passive to do that.


Now you can use distribution list to control what you send to each of the neighbors.


shahidrox Wed, 11/29/2006 - 23:58
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thnks for the reply but i have tried it see, in RA config-router mode i mentioned two neighbours

(config-router)# neigbour B (its ip)

(config-router)# neigbour C (its ip)

now in distribution list we normally use standard access list rite ? but i want to specify the destination also 1 network is for neighbour B n other is for neigbour C, how can i do tht can u tell me the exact distribution n access list plz

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