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Hanging Routes - MPLS VRF

Hi all,

We've a cell-based MPLS network (based on IGX 8420 UXM's/URM acting as the P and 7206 VXR's with RPMs acting as the PEs and 6509 MSFC's as CE's and connected with STM-1 to the IGX UXM's).

On those PEs...we're running MPLS VPNs for our customers and there're 2 PEs acting as Route Reflectors for all the other PEs for reflecting the MP-BGP routes for the VRFs.

The problem is that with the gigabit interface from CE to PE down or reloads or any interface flapping or without any reason....all of a sudden we found that a VRF customer that has for example 2 branches....one of them connected to POPX and the other branch connected to POPY complaining that there's no connectivity between the 2 branches although when issuing the command " sh ip route vrf Customer AAA " on the PE of POPX we found that the IBGP routes of the other branch are present in its VRF routing table.....but still the 2 branches cannot ping each other.

The same problem may be repeated for all VRF customers connected between those 2 POPs and aren't solved except when issuing the command on the PE of POP X "clear ip route (lpbk add of the PE in POPY)" or shutdown the Loopback Interface

After that command....everything is OK and the 2 branches can ping each other without problems.

So has anyone faced this problem before ??? and if yes what were the steps done to avoid it other than the famous workaround "clear ip route (Remote PE lpbk add)"??? or Shutting down the Loopback Interface

1 REPLY
Bronze

Re: Hanging Routes - MPLS VRF

I remember hearing about such a problem recently which is related to some bugs in the area of label distribution on specific hardware and software. You can check if it applies to the version and hardware that you are using.

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