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Multiple Sites Using Same BGP AS with Different Providers?

Hello,

Apologies in advance if this has been answered somewhere but I'm seeing an issue where I have multiple independant sites running BGP off my ASN with different advertised IP blocks and different ISPs.

Site 1

ASN XXXXX

Route Advertised: yyy.yyy.62.0/24

Site 2

ASN XXXXX

Route Advertised: yyy.yyy.63.0/24

Site 3

ASN XXXXX

Route Advertised: yyy.yyy.56.0/23

If I check the routing table from site 1 to see the routes from site 3, I don't see the route at all.  I'm guessing this is normal.  Is there a way to bypass this behaviour to get it to advertise inside the same AS?  If not, is there someway to get all 3 sites to see each other?

Thanks for your help

David

  • WAN Routing and Switching
1 ACCEPTED SOLUTION

Accepted Solutions

Re: Multiple Sites Using Same BGP AS with Different Providers?

Hello

By default to avoiding routing loops BGP will not allow prefixes that have its own ASN in them, however fro a CE perspective you can overide this by using the allow-as command

CE perspective

router bgp xx

neighbor x.x.x.x allowas-in

PE Perspective

neighbor x.x.x.x as-overide

http://ccieblog.co.uk/bgp/bgp-as-override-vs-allow-as-in

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

Please don't forget to rate any posts that have been helpful. Thanks.
1 REPLY

Re: Multiple Sites Using Same BGP AS with Different Providers?

Hello

By default to avoiding routing loops BGP will not allow prefixes that have its own ASN in them, however fro a CE perspective you can overide this by using the allow-as command

CE perspective

router bgp xx

neighbor x.x.x.x allowas-in

PE Perspective

neighbor x.x.x.x as-overide

http://ccieblog.co.uk/bgp/bgp-as-override-vs-allow-as-in

res

Paul

Please don't forget to rate any posts that have been helpful.

Thanks.

Please don't forget to rate any posts that have been helpful. Thanks.
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