BGP AS numbers?

[louis0001]

We have 50+ sites on our MPLS network. All are connected quite successfully and all have a completely individual private AS number eg router bgp 65001

We are about to bring a new site online and our telco provider has given us the details but this time with an AS number that we have on another site.

When I spotted this and pointed it out, our provider said that it was ok for our sites to have the same AS number and they didn't have to be unique to each site.
 

Is this correct?

[leonardolopez726]

Hi Louis,

It might work, it all depends on the kind of solution you've got in your network.

We all know that BGP loop prevention mechanism works checking the AS-path of the packet and it compares it with your AS. If any of the AS written in the AS-path match with your AS the update will be discarded and your router will not learn that update.

This might represent some problems with LantoLan communications.

According to that, you can use some features that BGP have:

BGP allowas-in: (http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/112236-allowas-in-bgp-config-example.html)

BGP as-override: (https://supportforums.cisco.com/document/87671/understanding-bgp-override-feature)

You can use any of them depending on your network needs.

I Hope this information could be useful to you.

Sorry about my english.

 

[Ruben Cocheno]

Hi,

They probably will use BGP as-override on their side