Tuesday, January 6, 2009

MPLS Traffic Engineering: PE to PE Tunnels Complete

I must confess, I made it thorough all the written exams so far without touching Traffic Engineering. I knew a tiny bit of theory, such as it relied on RSVP and inserted yet another label on the stack, but that was about it.

This first TE lab was a pretty good introduction. This link describes the configuration process really well.

In a nutshell, a tunnel interface needs to be created on the two endpoints. The tunnel gets configured as mode mpls traffic-eng, along with a bunch of other options under the tunnel interface.

Then, the mpls network needs to be configured to support this tunnel. This is accomplished through the monotonous configuration, on each router, of:
  • enabling mpls traffic engineering globally
  • enabling mpls traffic engineering on each interface between the tunnel endpoints
  • configuring ip rsvp bandwidth on each interface between the tunnel endpoints
  • configuring ospf (or isis) for traffic engineering on each mpls router
It seems if you miss a link in the path, little info is given as to which one you've missed. Instead, all you get is a message saying that the path isn't valid when you do a show mpls tra tun. Once all the links have been completed, the tunnel interface comes up/up.

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