Populating BGP from Connected or IGP routes

Eric C. Miller eric at ericheather.com
Mon Jan 23 20:46:49 UTC 2012

Hi all,

I'm looking for a best practice sort of answer, plus maybe comments on why your network may or may not follow this. 

First, when running a small ISP with about the equivilent of a /18 or /19 in different blocks, how should you decide what should be in the IGP and what should be in BGP? I assume that it's somewhere between all and none, and one site that I found made some good sense saying something to the following, "Use a link-state protocol to track interconnections and loopbacks only, and place all of the networks including customer networks into BGP."

Secondly, when is it ok, or preferable to utilize "redistribute connected" for gathering networks for BGP over using a network statement? I know that this influences the origin code, but past that, why else? Would it ever be permissible to redistribute from the IGP into BGP?

Thanks for everyone's input!

Eric Miller

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