Re: Complex real-life BGP problem

From: nenad pudar (nenad.pudar@gmail.com)
Date: Thu Mar 17 2005 - 16:35:22 GMT-3


I guess you are talking about having two bgp sessions with one
specific cust; one over directly connected link ,and the other one
ebgp multihop to the `new-next-hop router `` with higher LP
This is not bad idea but however it is not flexible
I would like to be able to play with the traffic from multiple
customers using below specified filter list 33

nenad

On Thu, 17 Mar 2005 14:04:11 -0500, Jongsoo.Kim@intelsat.com
<Jongsoo.Kim@intelsat.com> wrote:
> Nenad
>
> First of all, I don't know full topology of your network.
> But this is what I do.
>
> I will do two ebgp session between your ebgp peer and 1)the one you have now
> and 2)the new next-hop-router.
> And then I will increase local-preference of annoucement from the new
> next-hop-router.
>
> Regards
>
> Jongsoo
>
>
> -----Original Message-----
> From: nenad pudar [mailto:nenad.pudar@gmail.com]
> Sent: Thursday, 17 March, 2005 11:16 AM
> To: ccielab@groupstudy.com
> Subject: Complex real-life BGP problem
>
> Hi
> I want to change the bgp next-hop from being the router receiving some
> routes through EBGP (policy will apply to selcted routes) to be the
> other router in network (many hops away)
> This is for purpose of traffic balancing.
> The problem with this that if the new next-hop-router goes down I will
> be blackholing the selected routes from the router in question.
> So am looking for for some kind of policy that will change next-hop
> only if the new-next-hop router is up.
> Simplified config looks like this
>
> route-map NEXT-HOP PERMIT 10
> match as-path 33------ selected routes
> set ip next-hope NEW ROUTER
>
> route-map NEXT-HOP PERMIT 20
>
> neighbor backbone route-map NEXT-HOP out
>
> The only option I see so far is to use something like this
> set ip next-hop ADDRESS1 ADDRESS2
> Now according to some Cisco documents if ADDRESS1 is unreachible it
> will use ADDRESS2
> BUT IT DOES NOT SEEM TO BE WORKING
> EVEN IF ADDRESS1 GETS UNREACHEBLE all routers continue to have this
> address as next-hop marked with unaccessible.
>
> If anybody already tried to do this or know for some option I will
> appreciate help
> thanks
> nenad
>
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