H12-891_V1.0 Exam Dumps : HCIE-Datacom V1.0

Comprehensive and Detailed In-Depth Explanation:

In VXLAN encapsulation, the data frame is encapsulated as follows:

Original Ethernet Frame:The data packet to be encapsulated.

VXLAN Header:Contains the VXLAN Network Identifier (VNI) and other information.

UDP Header:VXLAN usesUDP (User Datagram Protocol)to transport the encapsulated data over an IP network.

Outer IP Header:Provides the source and destination IP addresses of the VTEPs.

Therefore, theUDP header(C) isencapsulated between the outer IP header and the VXLAN header.

DiffServ QoS model operates on per-hop behavior (PHB) and has these limitations:

A. ✅ Single-hop behavior; no end-to-end path awareness.

B. ✅ Cannot guarantee dedicated resources to individual users.

C. ✅ Does not address traffic bursts; congestion is still possible.

D. ✅ Queue limitations hinder fine-grained SLA assurance and deterministic delay.

Exact Extract – HCIE-Datacom QoS Section:

“DiffServ provides PHB without path-level control. It cannot guarantee SLA for individual users due to limited queuing mechanisms and lack of end-to-end visibility.”

FEC (Forwarding Equivalence Class) in MPLS is a group of packets that are forwarded in the same manner. MPLS can classify packets into FECs based on factors such as:

Destination IP address

Source address

CoS (Class of Service)

Application type

However, Fragment Offset, which is part of the IP header used for IP fragmentation, is not used in FEC classification. Fragment offset is more relevant to how IP packets are reconstructed and not suitable or used as a classification standard for forwarding decisions in MPLS.

Exact Extract - Huawei HCIE-Datacom V1.0 MPLS Chapter:

“FEC classification may be based on various parameters including destination address, source address, and even CoS values. However, fragment offset is not used as an FEC criterion, as MPLS forwarding occurs before IP reassembly.”