[c-nsp] mpls on one interface carried over an l2tpv3 on another interface

[Gert Doering]

Hi,

On Wed, Nov 28, 2007 at 05:24:27AM -0500, Joe Maimon wrote:
> On fa0/0/0.2 I run mpls.
> 
> on Fa0/1/0.2 I run l2tpv3 xconnect to another identicaly setup router in 
> another location.

So if I understand this correctly, you need the L2TPv3 tunnel to build
a "virtual ethernet" between two 7500s, that can then be used to tunnel
MPLS across it, from two other interfaces on the same set of routers?


7500 fa0/0 -(spit out MPLS)-> same 7500, fa0/1 -(tunnel via L2TPv3)->
  other 7500 -> ...?


It *should* work, but I wouldn't be surprised if things like this confuse
the ARP/CEF handling code of the box ("I can't learn that MAC address 
*here*, because it's mine, and used *there*").

> Should I expect mpls to transport the vrf packets?
> 
> It doesnt, ping vrf XXX a.b.c.d, where a.b.c.d is on the other router, 
> fails.

This question doesn't really grok.  Where does VRF come into this?

There's two things to diagnose this:

 - ping from 7500-1: fa0/0/0.2 <-> 7500-2: <mpls interface>
   - there is *no* MPLS involved here, just plain IP, possibly inside
     a VRF (depending on the 7500s are configured)
   - if that doesn't work, you have a problem with "bridging my own
     interface over my other interface", or maybe with "subinterface".

 - if that *does* work, you should check whether LDP/TDP and your IGP come 
   up on that link - which is then needed to transport MPLS frames.  But
   for a link with MPLS frames on it, you normally would not put it into
   a VRF, so this whole setup is confusing me somewhat.

Actually, if all you want is "transport VRF IP packets to router B", 
this whole setup is much too complicated.  Just setup an IPIP or GRE
tunnel, put it inside the VRF, and forward packets.

gert
-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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