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overlapping IPs

Hi Guys,

we have different services that are connected to our CEs through MPLS network.

PEs are connected to CEs using multiple EBGP peering on different subinterfaces (one for each service).. 

Now let's assume that there are overlapping IPs used on different VRFs (which is fine inside the MPLS network) but those IPs will be terminated to the CEs.

to give an example: let's say that CEs advertise network for service (A) that is part of VRF (A). 

and then they also advertise network for service (B) that is part of VRF (B). 

How would other CEs route traffic? will they be able to send traffic back to both VRFs or they will prefer the more specific subset and send all traffic back to VRF B ? 



Community Member

any thoughts ?

any thoughts ?

Community Member

Hi,Thats an interesting one


Thats an interesting one.

If the LAN side of the CE's maintained the VRF separation then of course, you would expect no problems with that.

if the CE's have a GRT for LAN side and if those two prefixes were leaked into that GRT, then I guess GRT would end up with the two routes from different sources, the longest prefix rule would mean that anything falling into the /29 would still go via vrf B and everything else would go via vrf A.

so it would mean that legitimate traffic for meant for destinations on VRF A would instead be sent via VRF B, while legitimate traffic for the for destinations on VRF B would always get there ok. Basically, the longest prefix routing rule would come into play and break /29 for VRF A.

I think the same would go for a non VRF aware CE which is receiving the two prefixes from upstream PE's.





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