Bgp advertisment to a specific neighbour !!

Unanswered Question
Apr 15th, 2008

Hi all, suppose i have 10 neighbours configured in bgp process of RA, now i want to advertise network 25.0.0.0/8 to only neighbour 12.0.0.1 in the same AS, i want to do it using the minimal set of commands, how can i do that ?? i dont want to advertise 12.0.0.0 to other neighbours except 12.0.0.1 ok

Thanks

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illusion_rox Tue, 04/15/2008 - 00:14

hi narayan, what i actually want is to tell the bgp process to advertise a particular prefix to a particular neighbour only, in case of conditional advertisement can you provide the configuration of my case ??,

Thanks

mohammedmahmoud Tue, 04/15/2008 - 00:30

Hi Ovais,

You need to do prefix filtering using prefix-list or route-map, for simplicity you can use a prefix-list that filters the undesired prefixes while permitting any other prefix.

The prefix-list entry that permits any prefix is:

ip prefix-list FILTER permit 0.0.0.0/0 le 32

Apply the prefix-list to the neighbor:

neighbor x.x.x.x prefix-list FILTER out

BR,

Mohammed Mahmoud.

illusion_rox Tue, 04/15/2008 - 00:44

Hi Mohammad, you mean to say that i want to deny prefix 12.0.0.0/8 to my 9 neighbours so i need to apply prefix-list out to 9 neighbours right ??

Now kindly try to get my point is that i want to define some condition on the network itself to be advertised to a specific neighbour !!

mohammedmahmoud Tue, 04/15/2008 - 01:10

Hi,

Ok, the only thing that comes to my mind right now is using peer group to group the 9 neighbors, but there is a trick here, you can't define a specific outbound routing policy to a single peer-group member, outbound routing policies can only be applied to the whole peer-group.

BR,

Mohammed Mahmoud.

illusion_rox Tue, 04/15/2008 - 01:51

hi Mohammad, i didnt noticed you were a CCIE, well i guess then what you are suggesting is perhaps the only option left, i need to ask something regarding the CCIE lab itself, what i know is that by the end of lab there should be full reachability, but we may be required to perform some filtering in which case a router may not have certain routes in Routing table so how come full reachability can be achieved ??

mohammedmahmoud Tue, 04/15/2008 - 02:08

Hi,

Yes, perhaps :) As for the full reachability in the CCIE lab, this excludes any route that was explicitly required to be filtered on a specific router(s), double checking with the proctor in such case is your best option.

BR,

Mohammed Mahmoud.

illusion_rox Tue, 04/15/2008 - 02:21

Mohammad can you also tell me that how much qos comes from a switching point of view ?, i mean to say how much area is covered by 3550/3560 switches in the lab ??

Thanks this is my last question :)

mohammedmahmoud Tue, 04/15/2008 - 03:23

Hi,

You are very welcomed :) Actually this is a question that i can't answer in details, because of 2 aspects, first this was never declared by Cisco anywhere, secondly according to the NDA i can't inform you with my exam details. But frankly speaking baring in mind the massive points that needs to be covered in the exam, i guess Catalyst QoS if covered won't be a big part.

For more details, the below link is a wonderful link about CCIE Catalyst QoS:

http://classroom.internetworkexpert.com/p95576427

BR,

Mohammed Mahmoud.

mohammedmahmoud Wed, 04/16/2008 - 02:51

Hi,

No, but beside the CoD and Cisco DocCD and your lab you'll find your way.

BR,

Mohammed Mahmoud.

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