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