[c-nsp] MPLS VPN with PE over GRE tunnels

[Bruce Pinsky]

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Ross Halliday wrote:
> It seems I made an error in the subject of my message, should read "MPLS
> VPN with CE over GRE tunnels"... Looks like a few people didn't read far
> beyond the subject line :P
> 
> Thank you Gert and Cristophe, I will give that a test tonight. Does the
> same sort of gotcha exist on the 7200 platform? I moved the interfaces
> over to that router, which also runs MPLS, and before I corrected the
> VPNv4 iBGP relationships the traffic worked fine when the 7204 sent
> packets out labeled for that default route (which caused them to be sent
> back via OSPF into an SVI). Once I fixed the BGP peering so that the
> 7204 learned the far VPNv4 route properly it exhibited the same problem
> as the 6509. The 7204 is a dinky ol' NPE-225 running 12.4(22)T.
> 
> Reading that page that Cristophe linked, I'm curious why this isn't
> default behavior. Is it just some magic knob to stump people on a CCIE
> exam or is there some performance impact or other side effects?
> 

No, the recirculation issue is only related to the 6500.  It has to do with
what operations can be performed in the hardware in a single cycle.  The
7200 is a software switching platform and would not have such a limitation.
 If you are having a problem on the 7200, there is something else going on
here.  We terminate DMVPN in VRFs for L3VPN on 7200's all the time without
issue.

Some additional troubleshooting info would be useful such as traceroutes in
both directions, ping tests from the CE site to the PE itself, etc to see
where the transit path is breaking down.  Also, complete configs would be
useful to see if anything jumps out.

- -- 
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bep

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