BGP AS numbers

Unanswered Question
Sep 2nd, 2008

I have the following BGP network:

10.0.20.0/24/AS65002---AS65000---AS65002/10.0.10.0/24

AS 65002 shows up in two different places, will 10.0.20.0 able to communicate 10.0.10.0 through AS65000?

Thanks,

I have this problem too.
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Giuseppe Larosa Tue, 09/02/2008 - 09:25

Hello Yuhui,

without additional configuration on some router the answer is no for the eBGP loop avoidance rule that doesn't accept a BGP advertisement that contain my own AS number.

You have two options:

a) router in AS 65000 use neigh ... as-override

b) both routers in AS 65002 use

neigh X allowas-in 1

Hope to help

Giuseppe

elguapooo Tue, 09/02/2008 - 14:55

Hot Topic Gentlemen,

Please post links and some guidance for carriers who support redundant ISP. We'd like to have the 2nd ISP DIA deployed and fully operational in 2008 (I could use a real raise). Thank you, Ladies | Gentlemen

Giuseppe Larosa Wed, 09/03/2008 - 23:41

Hello Michael,

some links on the subject:

BGP case studies: this provides concepts

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml

BGP multihoming config examples:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a008009456d.shtml

eBGP load-sharing examples:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml

These can be a good starting point.

Hope to help

Giuseppe

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