Wednesday, November 07, 2007

MPLS Label Stack in MPLS VPN, MPLS TE & AToM

+ In MPLS Layer 3 VPN, the top label in the label stack represents the IGP path to the next-hop Border Gateway Protocol (BGP) router, which is normally the PE router that originates the VPN routes. The bottom label represents a specific or aggregated VPN route.

+ In MPLS traffic engineering, the top label in the label stack represents the traffic-engineered path, and the bottom label represents the original Interior Gateway Protocol (IGP) path.

+ In Layer 2 VPN, the LDP top label usually represents the IGP path to the peering PE router, and the bottom label represents a Layer 2 VPN forwarder on the peering PE router.

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