Authentic Huawei Certification Exam H12-891_V1.0 Questions Answers

Let’s break this down step-by-step based on Huawei IS-IS VPN and multi-process behavior.

???? Configuration Summary:

Process 1: IS-IS for the global routing table

Process 2: IS-IS for VPN instance tt

Process 3: IS-IS for VPN instance rr

✅ Option C: Correct

Process 1 contains only global routing information.

The configuration of isis 1 does not include any vpn-instance keyword, meaning it is bound to the global routing table.

It does not interact with VPN routing tables unless explicitly configured with import/export mechanisms or route leaking (which is not shown here).

Huawei Datacom Reference:

“When an IS-IS process is not associated with a VPN instance, it belongs to the global routing table and only maintains global routes.”

(Source: HCIE-Datacom Study Guide v3.0 – Chapter: IS-IS for IPv4 and IPv6, Section: Multi-Instance Routing)

✅ Option D: Correct

Routing information of process 2 is isolated from that of process 3.

isis 2 is bound to VPN instance tt

isis 3 is bound to VPN instance rr

Each IS-IS process in Huawei VRF context maintains independent LSDBs and routing tables, and by default, they do not share routing information unless route leaking or redistribution is configured (which is not shown in the config).

Huawei Datacom Reference:

“IS-IS processes bound to different VPN instances operate independently and do not share routing information.”

(Source: HCIE-Datacom Study Guide v3.0 – Chapter: MPLS L3VPN with IS-IS)

In MPLS VPN, packets are forwarded using two labels:

Outer label (Transport Label) – Used by the MPLS backbone for forwarding.

Inner label (VPN Label) – Used by the egress PE to identify the correct VPN instance.

Explanation of Correct Options:

✅ A. The egress PE sends the data packet to the correct VPN based on the inner label.

The inner label is assigned by the egress PE and determines the final destination VPN instance.

✅ B. The penultimate hop removes the outer label before forwarding the data packet to a peer egress PE.

Penultimate Hop Popping (PHP) occurs when the second-to-last router (P router) removes the outer MPLS label before forwarding to the egress PE.

This reduces the processing overhead on the egress PE.

✅ D. The penultimate-hop device receives a packet with an outer label.

The outer label is used to forward the packet across the MPLS backbone.

Before reaching the egress PE, the penultimate router still has the outer label and processes it.

Incorrect Option:

❌ C. The IP data packet received by the egress LSR is without labels.

This is incorrect because the inner label (VPN label) is still present when the packet reaches the egress PE.

Only the outer label is removed by PHP, not the inner VPN label.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Label Processing

HCIE-Datacom MPLS Traffic Engineering and PHP Mechanism

Huawei iMaster NCE-Campus MPLS VPN Implementation Guide

In Huawei’s VXLAN implementation, the typical mapping between VNIs (VXLAN Network Identifiers) and BDs (Bridge Domains) is:

1:1 mapping — each VNI is uniquely associated with a single bridge domain.

This allows proper MAC learning and forwarding in the data plane for isolated tenant traffic.

Other mappings (N:1, 1:N, N:M) may be technically possible but not recommended or supported in most enterprise deployments.

Correct answer: B. 1:1