E-BGP neighborship between routers in the same AS??

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Apr 7th, 2010
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Hi,

does anybody know if exist a cisco feature wish allowed to configure a E-BGP session withing the same AS? That's mean, have a BGP session between neighbors which have the same AS number on teh comand "router bgp AS"


Thanks you very much

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Jon Marshall Wed, 04/07/2010 - 03:17
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maurizio.murano wrote:


Hi,

does anybody know if exist a cisco feature wish allowed to configure a E-BGP session withing the same AS? That's mean, have a BGP session between neighbors which have the same AS number on teh comand "router bgp AS"


Thanks you very much


Maurizio


Not as far as i am aware because if you define the same AS then it automatically becomes an IBGP session. You can allow advertised routes into an AS even if the AS is in the path by using the allowas-in command under the BGP config but i don't think that is what you are asking.


Jon

milan.kulik Wed, 04/07/2010 - 05:36
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Hi,


maybe using "neighbor .... local-as xxx no-prepend replace-as" on both sides

might make both routers pretending to be placed in different AS numbers.


But I never tested such a trick.


HTH,

Milan

Giuseppe Larosa Wed, 04/07/2010 - 06:10
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Hello Maurizio,


as Milan as noted neigh local-as could be the right tool for this request


I used local-as towards CE routers only on one side of the BGP connection


the neigh allowas-in could be of help you cannot eliminate the original AS from the AS path attribute (you should be able with the options suggested by Milan)


May I ask you what is the scenario for this specific request?

I guess you would like to perform load balancing between an eBGP route and a currently iBGP route


Hope to help

Giuseppe

maurizio.murano Wed, 04/07/2010 - 08:29
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Hi Guys, thanks you very much for your help.

Guislar, I am afraid but i don't know detail of teh senario. I've just tryed to help a colleague of mine who was wondering about that. Anyway I have turned him throught the Milan's note and he was gratefull. So thank you very much.


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