two bgp as

Answered Question
Jun 11th, 2008
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Is it possible to have two different BGP AS in the same router?

Thank's

Marcelo


Correct Answer by Harold Ritter about 8 years 11 months ago

Marcelo,


You cannot use this command on an iBGP peer. You can inverse the logic though, change your "router bgp" ASN to 65200 and use the local-as command on the peer to ASN 11664 instead as follow:


router bgp 65200

neighbor 77.1.248.25 remote-as 65200

neighbor 154.0.17.129 remote-as 11664

neighbor 154.0.17.129 local-as 65194 no-prepend replace-as


Regards,

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paolo bevilacqua Wed, 06/11/2008 - 04:42
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Yes, in a kind of virtual manner. That is because you can manipulate AS numbers in any way you want.

paolo bevilacqua Wed, 06/11/2008 - 04:49
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Are you familiar with BGP configuration and AS path manipulation ? All that is documented in the cisco manuals.

That is the pre-requisite for what you want to do.

MARCELO MATURO Wed, 06/11/2008 - 05:42
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I applied this configuration but I can't get the peering. There is the following error:


Jun 11 10:38:04: %BGP-3-NOTIFICATION: sent to neighbor 77.1.248.25 3/11 (invalid or corrupt AS path) 3 bytes 400200

Harold Ritter Wed, 06/11/2008 - 05:52
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Marcelo,


Can you send a bit more info about the topology and configuration that you are trying to implement.


Regards,

MARCELO MATURO Wed, 06/11/2008 - 06:06
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This is the configuration. I need peering with 2 differente AS. The AS 65200 see me as 65200 y de 11664 see me as 65194.



!

router bgp 65194

no synchronization

bgp log-neighbor-changes

redistribute connected

neighbor 77.1.248.25 remote-as 65200

neighbor 77.1.248.25 local-as 65200 no-prepend replace-as

neighbor 154.0.17.129 remote-as 11664

neighbor 154.0.17.129 send-community

no auto-summary

!

Correct Answer
Harold Ritter Wed, 06/11/2008 - 06:53
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Marcelo,


You cannot use this command on an iBGP peer. You can inverse the logic though, change your "router bgp" ASN to 65200 and use the local-as command on the peer to ASN 11664 instead as follow:


router bgp 65200

neighbor 77.1.248.25 remote-as 65200

neighbor 154.0.17.129 remote-as 11664

neighbor 154.0.17.129 local-as 65194 no-prepend replace-as


Regards,

Harold Ritter Wed, 06/11/2008 - 04:48
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Marcelo,


You can only assign one AS number to your BGP router process but you can change that AS number when you connect to BGP peers by using the local-as feature.


Regards,

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