Forwarding Equivalence Class (FEC)is a key concept inMPLS (Multiprotocol Label Switching), where packets with thesame forwarding characteristicsare grouped into an FEC and assigned a label.
Correct Answers (Cannot be Used for FEC Allocation):
A. Fragment Offset–Incorrect as an FEC allocation standard
Fragment offset is used forreassembling fragmented IP packetsat the receiver side.
It isnot relevant for MPLS label assignment.
B. Application Protocol–Incorrect as an FEC allocation standard
MPLSdoes not classify packets based on application-layer protocols(e.g., HTTP, FTP).
It worksmainly at Layer 2 and Layer 3.
Incorrect Answers (Valid FEC Allocation Standards):
C. Destination Address–Valid FEC allocation criterion
One of themost commonMPLS FEC classifications.
Packets with thesame destination are groupedinto the same FEC.
D. Class of Service (CoS)–Valid FEC allocation criterion
MPLS usesCoS-based traffic classification(e.g., Exp bits in MPLS headers).
Different CoS levels can be mapped to different labels.
Reference from Huawei HCIE-Datacom Documentation:
Huawei MPLS Technology Guide – FEC and Label Assignment
HCIE-Datacom MPLS VPN Configuration Guide
