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

Comprehensive and Detailed In-Depth Explanation:

BGP4+ (BGP for IPv6) uses the MP_REACH_NLRI (Multiprotocol Reachable Network Layer Reachability Information) attribute to advertise IPv6 routes. This attribute is part of BGP ' s multiprotocol extensions (RFC 2858), allowing BGP to support multiple address families, including IPv6.

MP_REACH_NLRI: Advertises reachable IPv6 prefixes along with next-hop information.

MP_UNREACH_NLRI: Used to withdraw previously advertised IPv6 routes.

Since IPv6 addresses are significantly different from IPv4 addresses in structure and length (128 bits), the traditional BGP update message format (which supports only IPv4) is insufficient. The MP_REACH_NLRI attribute solves this by carrying IPv6-specific information.

In MPLS LDP, there are two types of sessions:

Direct LDP sessions: Established between directly connected LSRs using LDP Hellos over a link.

Remote LDP sessions (also called targeted LDP sessions): Established between non-directly connected LSRs. These require manual configuration of the remote peer.

In this scenario, SWA and SWC are not directly connected, so a remote (targeted) LDP session must be set up.

For a remote LDP session:

You must configure the remote peer using the command:

[SWA-MPLS-LDP] targeted-peer x.x.x.x

Where x.x.x.x is the LSR ID of SWC (33.3.3.3 in this case).

The current configuration does not include this required step.

Thus, the correct statement is:

D. You need to create a remote peer and specify an LSR ID for the remote peer.

SRv6 Instruction Naming Conventions

SRv6 (Segment Routing over IPv6) uses segment identifiers (SIDs) with specific functions, indicated by instruction keywords:

✅ A. T: Searches a specified routing table to forward packets.

T (Table Lookup) → Performs a lookup in a specified routing table and forwards packets accordingly.

❌ B. M: Searches a Layer 2 forwarding table for unicast forwarding.

Incorrect! SRv6 does not use M for Layer 2 unicast forwarding.

✅ C. V: Searches a VPN instance routing table to forward packets.

V (VPN Routing Table Lookup) → Performs a lookup in a VPN instance (VRF) table for forwarding.

✅ D. X: Forwards packets through one or a group of specified Layer 3 interfaces.

X (Cross-connect forwarding) → Forwards packets via a specified Layer 3 interface or group of interfaces.

Reference from Huawei HCIE-Datacom Documentation:

Huawei SRv6 Configuration Guide – SRv6 SID Naming and Instruction Set

HCIE-Datacom Study Material – Segment Routing over IPv6 (SRv6) Functionality