BGP AS number

[dong-lee]

Hello,

Would I have any problem if I use the same BGP AS number from different location that aren't directly connected to each other?

We are tyring to set up a backup site, and there will no connections between the backup and main site. We were wondering if it would disturbed BGP routing table since BGP used AS path to route.

Thanks in advance

Dong

[vcjones]

This technically violates the BGP requirement that all BGP speakers in an AS be IBGP peers, it will work with one exception: you will not be able to learn routes to your other sites sharing the ASN via BGP (they will be discarded as looping routes). However, you should be able to use static routes to your ISP(s) to do the job.

The "correct" solution is to set up a VPN between your isolated sites and run your IBGP through that (you will still need static routes so that IBGP will know you use the local ISP to get to the other site). If set up correctly, this also prevents intersite traffic from traversing the Internet in the clear.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

[dong-lee]

Vincent,

Thanks for your reply. :)

Would be still a problem if two sites advertise two different network??

Backup site and Main site have separet ip range...

Thanks again

Dong

[vcjones]

No, in fact it is just the opposite. The two sites MUST only advertise different networks (unless there is a link between them, in which case you can run IBGP between them and have a legal configuration, but that was not your question :-).

Vincent C Jones

www.networkingunlimited.com

[dong-lee]

OK.

So we should be fine using same AS number as long as the two sites advertise different network.

Thank you very much

Dong