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Accepted
Andy Shinn
Asked: 2012-03-19 11:34:49 +0800 CST

How to prevent default route from propagating into iBGP?

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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 0.0.0.0/0

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?

routing bgp brocade policy-routing foundry

1 Answers

  1. Best Answer

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

    Try:

    prefix-list allow_default: 1 entries
     seq 5 deny 0.0.0.0/0

    Or:

    prefix-list deny_default: 3 entries
     seq 5 allow 0.0.0.0/1
     seq 6 allow 128.0.0.0/1
     seq 10 deny 0.0.0.0/0
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