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New Member

BGP question

I've 3 branches connected to MPLS IP VPN. Each branch have own private AS connected to ISP's AS.Two branches connected to each other.For example AS1 connect AS2 and both connected to AS11111(ISP). I want to advertise one route by both AS but use only one, the second in case of first failure.

Which solution i must to use - as-path prepend? For example AS1 advertised route without as-path prepend and AS2 advertised route with as-path prepend.

Should i see both paths at router in AS3?


Re: BGP question

As-path prepend will work as you describe. Since you ISP will only select the best route it will only have the shortest one in its routing table. This is the only route it will advertise to its neighbors. You will in your example only see the route advertised from as1 on as3. In the case of failure you will get the route from as2.

New Member

Re: BGP question

You could also potentially use advertise-maps. Watch for your own route coming back in from the other site, if it's not coming in, then advertise the route.