iBGP Questions

I am new to BGP and have a few question with iBGP

here is the current setup

RouterA - eBGP session to one of our upstream1 RouterA - iBGP to RouterB

RouterB - iBGP to RouterA

For some reason RouterB is not recieving any routes from RouterA via iBGP.

If I show the bgp table on RouterB it is empty yet the iBGP session is established correctly.

Any ideas?

Reply to
jamie.orzechowski
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IBGP will only advertise networks that are in an underlying IGP, including static routes. What other protocol or static routes do you have in place? Else Router A will not be advertising anything to Router B as those routes are not in an underlying interior protocol.

Reply to
Trendkill

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Reply to
Trendkill

With synchronization on this is certainly true. However you don't want this. If router A is receiving routes from the internet then of course you don't want a full internet routing table in your IGP!

Make sure that your iBGP config between A and B have;

no synchronization update-source Loopback0 (your IGP should provide routing between loopbacks) next-hop-self (so that when router A sends a BGP route to B it changes the next-hop and B won't have a connection to the transit provider)

I think that the key here is synchronization.

Can you provide your BGP configs?

Chris.

Reply to
Chris

I'm not saying turn up the whole internet routing table in an IGP, but simply summarize into a default route, or make sure that whatever networks you are pushing into IBGP are being advertised via an IGP. Sychronization will not fix the requirement for an IGP I don't believe.

Reply to
Trendkill

I obviously am sleeping at the wheel today. Synchronization should relieve the IGP requirement....although I still recommend an underlying IGP.

Reply to
Trendkill

With a BGP network you only need an IGP for each iBGP neighbor to be able to see each other in order to set up iBGP sessions. This is because they usually use the loopback addresses and are not always directly connected neighbors. As far as advertising BGP routes goes, synchronization should be off and you don't need to see any external routes in the IGP, just BGP.

He obviously has his BGP sessions set up so routing between A and B isn't an issue so I suspect that he has synchronization on. I've set up plenty of iBGP peers and never had issues with them receiving routes from other peers and full routes from our edge routers .. and our iBGP config is VERY simple. Nothing clever going on!

Router bgp 12345 no synchronization bgp log-neighbor changes neighbor LOCAL peer-group neighbor LOCAL remote-as 12345 neighbor LOCAL update-source Loopback0 neighbor LOCAL next-hop-self neighbor x.x.x.x peer-group LOCAL neighbor x.x.x.x description iBGP to something or other neighbor x.x.x.x password 7 blahblahvlah

Works like a charm. There's no redistribution between BGP and our IGP (IS-IS) at all.

Chris.

Reply to
Chris

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