Forwarding Equivalence Class (FEC) is a key concept in MPLS (Multiprotocol Label Switching), where packets with the same forwarding characteristics are 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 for reassembling fragmented IP packets at the receiver side.
It is not relevant for MPLS label assignment.
B. Application Protocol – Incorrect as an FEC allocation standard
MPLS does not classify packets based on application-layer protocols (e.g., HTTP, FTP).
It works mainly at Layer 2 and Layer 3.
Incorrect Answers (Valid FEC Allocation Standards):
C. Destination Address – Valid FEC allocation criterion
One of the most common MPLS FEC classifications.
Packets with the same destination are grouped into the same FEC.
D. Class of Service (CoS) – Valid FEC allocation criterion
MPLS uses CoS-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
