Thursday, November 13, 2008

SP Volume I Basic MPLS Complete

The biggest challenge here was in getting Dynamips up and running and configured. Fortunately, IE has a great guide which saved me a lot of work. I first tried to run it in Windows, but the performance was too poor. So I switched to Linux, and I can get the Vol I equipment up and running just fine.

The Basic MPLS lab was just what it says. Just needed to throw OSPF and BGP on a few routers and then put MPLS on the core. It was a nice exercise just to watch the pings propagate even though the core routers don't have a route to the final destination.

I had two mistakes in my configuration that I was able to correct pretty quicly. First, I missed mpls ip on one of the interfaces. Because it was missing, some of my hops were untagged in the mpls forwarding table. Simply checking the mpls neighbors at each router pointed me to the issue pretty quickly.

The second mistake was that I didn't put next-hop-self on the PE routers. This is necessary because the core needs a route to the next BGP hop, just not to the final destination. By deafult, iBGP does not update the next-hop and leaves it as the first eBGP hop.

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