BGP next-hop

Randy Bush randy at psg.com
Thu Sep 30 16:37:43 CDT 2010


i was recently bitten by a cousin of this

research router getting an ebgp multi-hop full feed from 147.28.0.1
(address is relevant)

it is on a lan with a default gateway 42.666.77.11 (address not
relevant), so it has

    ip route 0.0.0.0  0.0.0.0  42.666.77.11

massive flapping results.  

it seems it gets the bgp route for 147.28.0.0/16 and then can not
resolve the next hop.  it would not recurse to the default exit.

of course it was solved by

    ip route 147.28.0.0  255.255.0.0  42.666.77.11

but i do not really understand in my heart why i needed to do this.

randy




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