Free Huawei H12-891_V1.0 Practice Exam with Questions & Answers | Set: 8

Understanding SRLB (Segment Routing Local Block)

????What is SRLB?

SRLB (Segment Routing Local Block)is arange of local MPLS labelsused bySegment Routing (SR-MPLS).

These labels areonly relevant to the local routerand arenot advertised to other routers.

????Key SR-MPLS Label Blocks:

✅SRGB (Segment Routing Global Block)– Globally significant labels shared among routers.

✅SRLB (Segment Routing Local Block)– Locally significant labels, not shared.

Why is the Answer TRUE?

✅SRLB labels are only locally defined and are NOT distributed via IGP (OSPF or IS-IS).

✅They are used for local forwarding decisions within an SR-enabled router.

✅Only SRGB labels are advertised to ensure consistent global label assignment.

Real-World Application:

Traffic Engineering (TE):Uses SRLB forcustom local path optimizations.

Segment Routing Networks:Ensuresscalable MPLS forwardingwithout requiring full LDP signaling.

✅Reference:Huawei HCIE-Datacom Guide – Segment Routing Label Blocks (SRGB & SRLB)

Why is Free Mobility Not Based on VLANs or IP Addresses?

Free mobilityin Huawei CloudCampus implementspolicy-based user access controlbased onuser identity (rather than VLANs or IP addresses).

Users canmove across different network locationswhile maintaining their assignedsecurity and access policies.

✅How Free Mobility Works:

Policies are applied based onUser Groupsinstead of VLAN or IP.

UsesGroup-Based Policy Control (GBP)andSoftware-Defined Access (SDA)principles.

❌Incorrect Statement Explanation:

Traditional networks rely on VLANs and IP addresses for segmentation, butFree Mobility applies policies at the user level, allowing seamless access anywhere on the network.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Solution Guide – Free Mobility and Policy Control

HCIE-Datacom Training Material – Identity-Based Networking

Understanding BFD (Bidirectional Forwarding Detection)

BFDis ahigh-speed fault detection protocolused to monitor link failures inmilliseconds.

It operates atLayer 2 (Data Link Layer) and Layer 3 (Network Layer)to providefast convergence.

Why Can BFD Detect Failures in Milliseconds?

Useslightweight control packetsthat are exchanged between routers.

Works withOSPF, IS-IS, BGP, and MPLSto trigger fast convergence.

Detection time = (Transmit Interval) × (Detect Multiplier)

Example: If the interval is3msand the multiplier is3, failure detection takes9ms.

Why is the Answer TRUE?

✅BFD achieves millisecond-level detectionby sending rapid probe packets.

✅Used in high-availability networkswhere link failures must be detected inreal-time.

Real-World Application

Service Provider Networks:BFD improves network resilience by detecting link failuresfaster than traditional routing timers.

Enterprise WANs:Used inSD-WANsto switch paths dynamically.

MPLS Fast Reroute (FRR):Works withMPLS Traffic Engineeringfor near-instantaneous failover.

✅Reference:Huawei HCIE-Datacom Guide – BFD for Fast Link Failure Detection

Route Target (RT)is aBGP extended community attributeused inMPLS Layer 3 VPNs (L3VPNs)to control theimport and exportof VPN routes between differentVPN instances (VRFs).

Explanation of Correct Answers:

✅A. Each VPN instance is associated with one or more pairs of VPN Target attributes, used to control VPN routing information advertisement and reception between sites.

Each VRF (VPN Routing and Forwarding instance) has an associated RTthat determines which routes areimported and exportedbetween VPNs.

RTs enableinter-VPN communicationwhile maintaining separation between VPN customers.

✅B. Export Target and Import Target are independent of each other and support multiple values to implement flexible VPN routing information advertisement and reception control.

TheExport RTspecifies which routes should be advertised.

TheImport RTspecifies which routes should be accepted into a VRF.

These can beconfigured independentlyto control traffic flow between VPNs.

✅C. RTs are classified into two types: Export Target and Import Target.

Export Target: Defineswhich VPN routes are advertised.

Import Target: Defineswhich VPN routes are accepted.

A VPN instance can have multiple RTsto allow flexibility.

✅D. The RT value is advertised to neighbors through the BGP extended community attribute in Update messages.

RTs are carried in BGP UPDATE messagesas part of theBGP extended community attribute, enabling VPN route exchange between PEs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Route Target (RT) Concepts

HCIE-Datacom Study Material – BGP Route Advertisement in MPLS VPNs

Huawei Switch Deployment Methods in CloudCampus

✅A. DHCP Option 148– Used forautomatic device registrationin iMaster NCE-Campus.

✅B. CLI (Command-Line Interface)– Traditionalmanual configuration methodusing the command-line interface.

✅C. Web Interface–Web GUI-basedconfiguration for easy management.

✅D. Huawei Registration Center–Cloud-based automatic registration and provisioningfor plug-and-play deployment.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Deployment Guide – Device Onboarding Methods

HCIE-Datacom Training Material – Zero-Touch Deployment (ZTP) in CloudCampus

A. The device sends sampled data every second→Correct, since sample interval is 1000ms = 1 second.

B. The subscription mode is static subscription→Correct, as shown by Sub state: PASSIVE. Passive indicates astatic subscription.

C. The IP address of the device is 192.168.56.1→Incorrect— this IP address is thedestination (telemetry collector),notthe device’s own IP.

D. The subscription name is Sub1→Correct, as per Sub name : Sub1.

Correct answer: C. The IP address of the device is 192.168.56.1— this is incorrect because it's actually the collector’s IP, not the device's.

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 requiremanual configurationof the remote peer.

In this scenario, SWA and SWC arenot directly connected, so aremote (targeted) LDP sessionmust be set up.

For a remote LDP session:

Youmust configure the remote peerusing the command:

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

Where x.x.x.x is theLSR 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.

Comprehensive and Detailed In-Depth Explanation:

In SR-MPLS, ifprefix SIDs conflict, the following principles are applied:

Prefix with a smaller value (numerically lower SID) wins.

If the prefix length is the same, the lower SID value is selected.

In this case:

Both1.1.1.1/32 2 (A)and1.1.1.1/32 1 (B)have the same prefix length.

SinceSID 1is numericallysmallerthanSID 2,B (1.1.1.1/32 1)is selected.

The other routes (C and D) have different prefixes and do not directly conflict.

SRv6 Instruction Naming Conventions

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

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

T (Table Lookup)→ Performsa lookup in a specified routing tableand 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) tablefor 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

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Comprehensive and Detailed In-Depth Explanation:

ThegRPC-based telemetry protocolutilizesprotocol buffers (.proto files)to define the structure and data format used in communication between a client and a server. In Huawei's telemetry architecture, these files are categorized based on their roles in the data model.

1. RPC Layer:

File:huawei-grpc-dialin.proto

TheRPC layer (Remote Procedure Call layer)handles communication between the client and server.

The filehuawei-grpc-dialin.protodefines thegRPC service interfaces, message structures, and procedures for remote method invocation.

It is essential forestablishing communicationandinvoking telemetry data collection.

Function:Managesdial-in and dial-out connectionsbetween the telemetry client and the server.

2. Telemetry Layer:

File:huawei-telemetry.proto

Thetelemetry layeris responsible forcollecting, packaging, and exporting telemetry data.

The filehuawei-telemetry.protocontains thedata modelused for telemetry reporting, includingstreaming data formatsandtelemetry messages.

It defines how thecollected datais organized and transmitted.

Function:Provides astructured way to export telemetry datain real-time or batch mode.

3. Service Data Layer:

File:huawei-debug.proto

Theservice data layercontains data models related todiagnostics, debugging, and operational data.

The filehuawei-debug.protois used tocollect debugging informationfrom network devices.

This file is crucial fortroubleshooting and monitoring the healthof the system.

Function:Facilitatesdebugging and diagnostic telemetry data collection.

Why This Mapping Is Correct:

The mapping is based on thefunctional role of each layerand thepurpose of each .proto filein the Huawei gRPC-based telemetry architecture.

Correctly identifying the file location is crucial foreffective telemetry configurationanddata collection.