Huawei H12-891_V1.0 Exam With Confidence Using Practice Dumps

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

Comprehensive and Detailed In-Depth Explanation:

The diagram shows a WAN network where Segment Routing (SR) is used in conjunction with the iMaster NCE controller. The network consists of Data Centers (DCs), Branches, Provider Edge (PE) routers, and Route Reflectors (RR) within AS 65600. Let ' s analyze each network technology and its placement in the scenario.

1. BGP-LS (Border Gateway Protocol - Link State):

Application Location: 1 (PE to RR)

Explanation:

BGP-LS is used to collect and distribute network topology information from the IGP (Interior Gateway Protocol) domain.

It enables the iMaster NCE (controller) to learn about the network topology and SR information from PE routers.

The PE routers send their link-state information to the RR using BGP-LS.

Why Location 1:

The RR collects topology data from PEs and forwards it to the controller for path computation.

2. BGP (Border Gateway Protocol):

Application Location: 2 (RR to iMaster NCE)

Explanation:

Standard BGP is used for route distribution and network connectivity.

The RR uses BGP to exchange route information with the controller (iMaster NCE).

Why Location 2:

The RR aggregates routes and exchanges them with the iMaster NCE for centralized management.

3. MP-IBGP (Multiprotocol Internal BGP):

Application Location: 3 (PE to PE)

Explanation:

MP-IBGP is used to exchange VPNv4 and VPNv6 routes between PE routers within the same AS.

It allows PEs to advertise VPN routes across the backbone network.

Why Location 3:

PEs need to communicate VPN-related information within the AS, ensuring end-to-end connectivity between DCs and branches.

4. BGP SR-Policy/PCEP (Path Computation Element Protocol):

Application Location: 4 (iMaster NCE to PE)

Explanation:

BGP SR-Policy and PCEP are used by the controller to distribute SR policies to the PE routers.

The iMaster NCE calculates optimal paths and sends the SR policies to PEs via BGP SR-Policy or PCEP.

Why Location 4:

The controller programs the Segment Routing paths directly to the PEs for optimal traffic engineering.

Why This Mapping Is Correct:

The mapping is based on the roles and functions of each protocol within the SR-based WAN architecture. The controller uses BGP-LS to learn topology, BGP for route reflection, MP-IBGP for VPN route exchange, and BGP SR-Policy/PCEP for path computation and distribution.

When selecting core devices for a WAN in enterprise networks, considerations typically include:

Service volume: Ensures the core device can handle expected traffic.

Physical location: Important for latency, redundancy, and network design.

Node quantity: Affects topology, scalability, and routing complexity.

Device naming conventions, however, are purely administrative and do not affect the functional selection of core devices.

Correct answer: A. Device naming conventions