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New Member

what is better redistribute BGP into IGP or use IBGP


We have two big offices ( US & EUROPE). We do not run the same IGP for political reasons at the 2 locations. We are connected Via a DS3 connection. We want to use EBGP to connect the 2 AS.

My question is that should i redistribute ebgp into my igp or should i use ibgp to propagate routes from the other AS.

New Member

Re: what is better redistribute BGP into IGP or use IBGP

Though for a few routes you can redistribute ebgp into igp but the recommended option is to use ibgp.


Cisco Employee

Re: what is better redistribute BGP into IGP or use IBGP

Running iBGP would definitely help if you have multiple interconnection points between the two networks and you want to implement a consistent routing policy between the two ASes.

This would help the multiple exit points to selectthe best path to a given destination in the other AS and the exit point with the best path could then redistribute this route into the IGP.

Let me know if I answered your question,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
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Re: what is better redistribute BGP into IGP or use IBGP

I'd say run iBGP, as well, if you want to gain full routing information from the other network. The problem is this entails rolling iBGP out in both networks, all the way to the edges of both networks. Instead, another option would be to aggregate the routes, nail up static routes at the borders to null 0's for these aggregates, and then advertise these statics through redistribution into your IGP. As long as you're running iBGP between the border routers (eBGP speakers), then you shouldn't have any routing black holes and such.

I think this concept is covered, though not quite in this way, in the section on originating routes in Practical BGP.