[c-nsp] mpls-te - dynamic latency?

[christian.macnevin at uk.bnpparibas.com]

Thanks guys.

We do also need to route traffic to different tunnel endpoints - the sites 
we're talking about are multihomed and generally
one PE will have a high-latency link and one a low latency link. Is that 
going to require a further feature? (ie: do I need
DS-TE after all?)

Cheers
Christian (off to RTFM, honest)





Internet
oboehmer at cisco.com

04/04/2006 23:15

To
Christian MACNEVIN
cc
cisco-nsp
Subject
RE: [c-nsp] mpls-te - dynamic latency?






> Well, we'll be migrating from eigrp, not ospf, so yes, we do need
> is-is :) 

Oh, ok, right, you obviously need ISIS or OSPF..

> And as far as ds-te goes, I guess I need to understand that feature a
> little better to comment whether I feel I need 
> it just yet, But the end goal (whether it's that feature or not) is
> that we'd the tunnel to be as visible to the routing protocol as poss
> (autoroute i guess) and be routing traffic into those tunnels based
> on dscp markings. If I can  avoid 'invisible' mechanisms like pbr,
than I will.

Aaron mentioned CBTS, which is able to achieve this without PBR or
anything, but it requires parallel tunnels between head and tail, then
you could use autoroute and CBTS to send the traffic over the respective
tunnel.
DS-TE doesn't help you here at all, DS-TE essentially just makes sure we
don't send too much delay-sensitive traffic over links by using distinct
BW pools. It does not address forwarding traffic down the tunnel in any
way.

> Also, it's not just a matter of making sure the low latency path is
> chosen, but that non-latency-dependent traffic will use the other
link.

With this objective in mind, I guess parallel tunnels with CBTS will do
what you want.

> As for using the affinity bits, cheers, I'll look more into that.

You definitly need this to make sure that the "voice" tunnel only uses
those links and the best-effort tunnel uses other links. It obviously
requires discipline when setting up the links..

Multi-Topology Routing would be another option, but this feature is not
there yet..

                 oli



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