BGP Best External Explained

Loads of niche features got crammed into (MP)BGP and MPLS since I wrote my MPLS books, most of them trying to tweak BGP (a scalable and reasonably slow routing protocol dealing with behemoth tables) to behave more like an IGP would.

It looks like we’ll never see updated versions of the books, so I’ll try to cover the new features with short videos. The first one on the list: BGP Best External – a mechanism that speeds up MP-IBGP convergence in primary/backup PE-CE scenarios using EBGP.

More information

Watch the video

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8 comments:

  1. Herb 30 May 2013 18:05
    The BGP 1.0 and MPLS course-ware you wrote is some of the best pieces of course-ware out there. I would love to see you do more work with Learning@Cisco
    Replies
    1. Ivan Pepelnjak 31 May 2013 08:55
      Ah, those were the days. There were quite a few reasons those materials turned out as they did, including the fact that we created them based on real-life teaching experience of several instructors going back almost a decade.
  2. Anonymous 30 May 2013 18:57
    Thanks, Ivan, waiting for another feature video.
  3. Anonymous 30 May 2013 23:01
    Hi Ivan,

    Using different RD per vrf per pe would also provide the same benefits?
    Replies
    1. Ivan Pepelnjak 31 May 2013 08:57
      RD-per-VRF solves the "load balancing beyond RR" problem (which is also solved with AddPath).

      In this scenario it won't help - the PE router with the backup link will import IBGP VPNv4 route with a different RD into its BGP table (based on RT settings), select it as the best, and thus stop advertising its VRF EBGP route to IBGP peers.
    2. Anonymous 04 June 2013 07:43
      Thanks for correcting me. I have learned a ton from your posts and mpls books. The fail over solution you have outlined in this post is my go to solution /w communities. Eager to start labbing this and improving my offering.
  4. Anonymous 03 June 2013 16:14
    Hi Ivan!

    Thanks for the great explanation.

    Would you please also give your advise on how the described feature inter-operates/integrates with BGP Multipath.

    My view is that when BGP Multipath is enabled in load-balancing scenario, one doesn't need any additional tweaks like "BGP Best external", could you please share your expert view on that?
    Replies
    1. Ivan Pepelnjak 03 June 2013 16:15
      BGP Multipath does not work when the two external BGP routes are not (nearly) identical, which they shouldn't be in primary/backup scenarios.
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