From: Sergey Golovanov (sergey.golovanov@iementor.com)
Date: Thu Jan 25 2007 - 19:24:46 ART
you are trying to do source based routing, right? so you have no choice but rely on policy based routing. You can use combination of "set ip next-hop, interface, default next-hop, default interface" to achieve your desired behavior. Ask providers to advertise a /32 loopback to you. One provider will send you A/32, another provider will send you B/32. Then in your PBR route-map set next-hop to A and B for traffic sourcing from .188. and set next-hop to B and A for traffic sourcing from .189. Once the next-hop route disappears from the RIB, it should use backup.
The only thing is return traffic, you can't really guarantee that return traffic will come back from the same provider. It depends on how your provider is peering with AS'es where you send traffic.
I'm pulling this out of my head, you have to test it.
--------------------------------------------------------------------
Sergey Golovanov, CCIEx5 (R&S/Security/Voice/Service Provider/Storage)
"Please, don't ask me for my ccie #, there are reasons why I can't release it"
ieMentor Instructor and Content Developer
sergey.golovanov@iementor.com
http://www.iementor.com
> -------Original Message-------
> From: Stefan Grey <examplebrain@hotmail.com>
> Subject: BGP real world interesting question:)
> Sent: Jan 25 '07 16:54
>
> Hello guys,
>
>
> R2 R3
> | |
> |--R1---|
> / \
> .188 .189.
>
> Question is following, hope will be interesting:
> Between R1 and R2 is EBGP, between R1 and R3 is also EBGP. R1 is the router
> in the company and is in the global AS asigned to the company. R2 belongs to
> first provider, R3 belongs to the second provider. Networks .188 and .189
> are directly connected to the R1 router. Network 144.3.3.0 is advertised to
> R1 from routers R2 and R3. The expectations are following: when the hosts
> from .188 network want reach 144.3.3.0 network the packets should go to R2
> router, when the hosts from .188 want communicate with 144.3.3.0 the packets
> should go through R3 router. When the logical connection between R1 and R2
> fails, say there is no neighborship... all traffic from all neighbors should
> go to R3. And vice versa when connection to R3 fails all traffic should go
> through R2 router. We can change config on any of the routers and solution
> could be any.... Do you have any ideas how is it possible to acheeve it???
> How to acheeve it with only R1 as is??? Is it possible at all??
> Please help. Your ideas are highly appreciated. This is the question which
> arised in one of the big banks which is actually my key account.
>
>
> P.S The only idea I had was add another router R4 on the companies edge so
> that each of two routers would be connected to one provider and than using
> weight attribute achieve the needed functionality. Do you have any other
> ideas. Is it somehow possible to achieve this not changing current
> topology??
>
> Thank you very much!!!
>
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This archive was generated by hypermail 2.1.4 : Thu Feb 08 2007 - 23:46:57 ART