Re: [nsp] Mapping traffic into MPLS tunnels

From: Eric Osborne (eosborne@cisco.com)
Date: Wed May 22 2002 - 18:20:28 EDT


On Wed, May 22, 2002 at 05:30:33PM -0400, Ravichander Vaidyanathan wrote:
>
> Thanks much for the responses. Is policy based routing supported on vrf
> interfaces? My impression (at least a few IOS versions ago), was that it
> was not...
>

No, it isn't. If you want to do any sort of decision-making on a VRF
interface, you need to do it on destination IP address. You can play
games with setting next-hop differently for different destination
routes (based on community, etc), but if you need to distinguish
between traffic destined to the same IP address and coming from a VRF,
you're currently limited to destination-based routing.

eric

> Ravi
>
> On Wed, 22 May 2002, Sean Crocker wrote:
>
> > Eric,
> >
> > >> >Is there any other technique that allows one to have more control over the
> > >> >traffic that can be mapped into an MPLS tunnel? (Say by specifying an
> > >> >access list to map the traffic, or by using other IP header fields etc.?)
> > >>
> > >> Sure, policy based routing. You match packets based on
> > >> criteria you define, then you "shunt" the matched packets
> > >> across the LSP (out the Tunnel interface).
> > >
> > >you can also do forwarding-adjacency if you run ISIS; very similar to
> > >autoroute, though, and doesn't really solve any additional problems.
> >
> > Definitely, although it should also be clarified that neither
> > forwarding-adjacency nor autoroute matches packets on stuff
> > like IP header fields, source addr, etc :-) ... and that
> > "forwarding-adjacency" makes the LSP known as a link to all
> > routers in the cloud (similar to juniper, which can also do it
> > in OSPF), whereas autoroute just makes the LSP known only to
> > the local routing instance.
> >
> > Sean
> >
> >



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