I have 2 Foundry FESX448 switches which have external BGP connections. Each of them receive a default route. These 2 switches also have a BGP session configured between themselves and advertise routes to each other as iBGP.

I only want one of the switches to be the primary gateway as I am trying to move the traffic off the other switch. I tried limiting the announcement of the default gateway using the following prefix list configured as the outbound filter for the primary switch:

prefix-list deny_default: 1 entries
     seq 5 deny

But this seems to block the default gateway and other subnets connected on the switch. I am only trying to block the default gateway. But I still need to get to directly connected and static routes on the secondary switch.

already have default originate removed from the neighbor BGP config. The received default route from my ISP is the one being re-advertised.

What is a good way to accomplish this?

1 Answer 1


Not really knowing anything about these devices specifically, two ideas come to mind.


prefix-list allow_default: 1 entries
     seq 5 deny


prefix-list deny_default: 3 entries
     seq 5 allow
     seq 6 allow
     seq 10 deny
  • The second gets the job done it looks like. Though it isn't pretty...
    – Andy Shinn
    Mar 20, 2012 at 17:16

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