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New Member

MPLS Inner Label Question

As per the Cisco MPLS/VPN architectures book, the egress PE does "a lookup on the second label, which uniquely defines the target VRF" (page 163). My question is - If the second label is used to determine which routes learnt from a MPiBGP peer goes into which VRF, then why do I need route targets ? I believe that route target values carried as part of the BGP extended community attributes are used to determine which routes are imported into which VRF. Can anyone help me reconcile the two concepts ?


New Member

Re: MPLS Inner Label Question

Maybe I need some coffee - but I think I now see the error in my own qs. The inner/outer label is used during the packet forwarding operation, while the RT is used to determine what routes are imported into the routing table, during the route distribution stage. So, two different stages with two different uses. I think I'll go make myself a cup of coffee now.

Cisco Employee

Re: MPLS Inner Label Question

You are absolutely correct. One has to do with the forwarding plane and the other one with the control plane.

Please pour me a cup too ;o)

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
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