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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: eBGP, iBGP, injecting networks
Note - I got confused by the subject and everything myself. The routes you have locally would not be from IBGP but just directly through IGP (i.e. OSPF or EIGRP etc). I don't think you can really do IBGP if routers are not configured with the same ASN. On Fri, 20 Feb 2004, william(at)elan.net wrote: > > Ok. The way I read this is that you're redundant as far as one of your > upstream links going down - it'd not cause complete meltdown as that > router that had that link would still be announcing that space to the > other router (over EBGP) and then to the net. > > What you're worrying then is what happens if actual router is down, right? > But that begs the question of how you're getting the routes that router is > announcing in the first place. Is it coming from some other "edge" router > (that is also talking over local net to your 2nd core router)? > > If so each of your routers has complete local routes table through IBGP > and you are not announcing it all because you're using static "network" > statements in BGP config. In that case my suggestion would be to drop EBGP > connection between routers and have each router announce entire ip space > but put up 'as-path prepend' statements with the other adding the other > router's ASN for routes that you want to be considered as being primary > from that other router. Now exact configuration suggestion would depend on > what hardware the routers are, i.e. is it cisco, etc. > > P.S. I've never been in situation of having to merge two ASN's or in situation > you describe, so possibly people who have would have better suggestions. > > On Fri, 20 Feb 2004 [email protected] wrote: > > > > > greetings list, > > > > hoping someone can hook me up on the right way to do this. > > > > --- > > > > we have two ASN's we control. > > > > we have two border/edge routers (1 in each ASN) that talks to a > > different backbone provider. > > > > the two border routers peer with eachother over eBGP and also are in > > the same OSPF process. (we are working to merge them into the same > > BGP ASN) > > > > my question is this: > > > > how do we achieve router redundancy between these two routers? > > > > currently if we lose a transit link, the traffic will flow fine out > > the other pipe. > > > > but we don't have BGP network statements in router 2 that exist in > > router 1 and we don't have BGP network statements in router 1 that > > exist in router 2. > > > > so the routes injected into BGP from router 1 will get withdrawn right > > if router 1 dies? > > > > is it a problem to announce the same networks from two different eBGP > > peers to two different upstreams? > > > > ------ > > > > if you are still reading, thanks! > > > > to clearify some more- > > > > current setup: > > > > current setup: > > > > ASN 1 (we're not Genu!ty- just using for an example) > > > > :) > > > > ASN 1 injects all of its own space and announces this space to > > Above.net and ASN 2 > > > > ASN 2 injects all of its own space and announces this space to Savvis > > and ASN 1. > > > > so stuff out on the net looks like: > > > > 1 6461 etc etc > > > > and > > > > 1 2 6347 > > > > ------- > > > > 2 6347 etc etc > > > > and > > > > 2 1 6461 etc etc > > > > ------- > > > > so, you see we are prepending on of our AS's on the way out. > > > > the problem is tho, we only have 1 router in each respective Autonmous > > System injecting address space. if we lose that router, we lose > > announcing that ASN's space. > > > > is it totally going to cause probs to have routes originating from two > > different AS's? routing loops would be a real drag. > > > > what about having an iBGP router in AS 1 inject the same space as the > > border router in AS 1? this other router also peers with AS 2.... > > > > thanks a lot! > > jg
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