BGP Data Center

Unanswered Question
Jun 17th, 2007

Dear Community

We have two data centers (say A and B)which connected to the service provider. We are using BGP. The two data centers have the same AS, say 12345. Both data centers connect to the service provider.

If data center A advertises a network info, say network 10, to the service provider which replace the 'AS 12345' with her AS and sends the network info

back to data center B.

It applies to data center B as well.

Any ideas why the replacement of AS happens?????

Thanks in advance

Kelvin Cheung

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Overall Rating: 5 (1 ratings)
Edison Ortiz Mon, 06/18/2007 - 05:49

Your ISP will strip any private-AS coming from you since they aren't allowed in the internet.

If you want data center B to see data center A actual AS, you must create a peer between the data centers.

cheung.kelvin Mon, 06/18/2007 - 16:55

I am terribly sorry that I shall mention my network is a private network.

Please answer the question again!!!

Thanks in advance??

Kelvin Cheung

Edison Ortiz Mon, 06/18/2007 - 17:17


I believe I answered the question. For instance:

your AS is 65005 and the ISP AS is 105, when you send any network advertisement to 105, AS 105 will strip your AS (65005) because that AS is not allowed in the internet. The AS 65005 was only created to peer between your network and the ISP, not to be advertised to the internet.


cheung.kelvin Mon, 06/18/2007 - 18:05

Dear HTH

We are private network as mentioned before and NO internet connection. My service provider allows us to use private AS without stripping off my private AS. We have a number of sites, including two Data Centres, forming a WAN network using BGP with one private AS allocated in each site.

Back to my original question, the two Data Centres, having a separate physical locations, share the same AS. For some reason, my Service provider replaced her AS with my AS, but not happened at the other sites.


Kelvin Cheung

Edison Ortiz Tue, 06/19/2007 - 05:33

Can I see the config from the sites working as expected vs the sites not working as expected ?

Have you contacted your Service Provider and explained the problem to them ?

I believe it has nothing to do with your config, but a config on the service provider side.


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