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Routing & Switching · Intermediate

Forwarding Equivalence Class (FEC)

A group of packets forwarded the same way through an MPLS network, mapped to the same label.

Definition

With LDP, each IGP prefix is typically an FEC. The ingress LER assigns packets to an FEC and pushes the corresponding label, so all packets in that FEC follow the same LSP.

Example

All traffic to PE loopback 10.255.0.4/32 forms one FEC.

Exam tip

FEC is assigned once at ingress; core routers never reclassify by IP.

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