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.
router bgp 123
 network backdoor


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