BGP Notes – Backdoor Routes

  • The fact that eBGP has an AD of 20 can be a problem.
    • You may have a very short path via EIGRP (or OSPF or RIP or whatever other IGP), but the longer eBGP path will be preferred.
  • For God’s sake, do not lower the AD of EIGRP! ┬áHavoc will ensue.
  • Using backdoor routes causes eBGP routes to have an AD of 200.
    • Allows the shorter-path IGP routes to be added to the routing table.


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Aaron Conaway

I shake my head around sometimes and see what falls out. That's what lands on these pages. If you have any questions, the best way to contact me is through Twitter at @aconaway.

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