MPLS Forwarding and Next-Hop Tables Overview

An MPLS forwarding table determines how MPLS handles received MPLS packets. When an MPLS packet arrives on an MPLS major interface, MPLS looks up the outermost MPLS label of the received packet in the relevant MPLS forwarding table.

The entries in the MPLS forwarding table map labels to next hops. Each entry in the MPLS forwarding table points to an entry in the MPLS next-hop table. Each MPLS next hop points to either an interface or another MPLS next hop. The chain of MPLS next hops, which ends at an interface, informs MPLS which labels to push and where to send the MPLS packet.

For RSVP-TE tunnels, minor interfaces are created in addition to the forwarding table and next-hop table entries. One minor interface is created of each in/out segment of a tunnel. the purpose of these minor interfaces is to attach QoS and policy to an LSP.

MPLS forwarding tables consist of the following:

The signaling protocols add entries to the MPLS forwarding tables. You cannot manually create an MPLS forwarding entry. The signaling protocols set the following attributes for each entry placed in the forwarding table:

See Monitoring MPLS , for information about enabling statistics collection for MPLS forwarding table entries.

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