Free Huawei H12-891_V1.0 Practice Exam with Questions & Answers | Set: 2

Authentication Header (AH) in IPsec

TheAuthentication Header (AH) protocolis part ofIPsecand providesauthentication, integrity, and replay protectionbutdoes NOT provide encryption.

✅B. AH provides data origin authentication.

Ensures thatpackets come from a trusted sourceusing cryptographic signatures.

✅C. AH provides anti-replay protection.

Usessequence numbersto prevent attackers from replaying old packets.

✅D. AH provides data integrity authentication.

Ensuresdata integrityby verifying that packetshave not been tampered withduring transmission.

❌A. AH provides packet encryption – Incorrect!

AH does not encrypt packet contents.It only authenticates headers.

ESP (Encapsulating Security Payload) is used for encryption in IPsec.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPsec Configuration Guide – AH vs. ESP

HCIE-Datacom Training Material – IPsec Security Mechanisms

Comprehensive and Detailed Explanation:

Thereset isis allcommand resets theentire IS-IS process, including:

✔Neighbor adjacencies

✔LSDB (Link-State Database)

✔All IS-IS-related statistics

Key Points:

This commandresets IS-IS completely, causingtemporary route convergence delays.

All IS-IS statistics are clearedbecause the process restarts from scratch.

Since the question states thatIS-IS statistics are not cleared, which is incorrect, the correct answer isFALSE.

????Reference:Huawei HCIE Datacom – IS-IS Troubleshooting and Reset Commands

Comprehensive and Detailed Explanation:

Port isolationis a feature used to enhance security andnetwork segmentationby restricting communication between certain switch ports atLayer 2while allowing them to communicate throughLayer 3.

Layer 2 Communication:Devices within the same VLAN can communicate with an upstream gateway or router.

Layer 3 Isolation:Devices cannot communicatedirectlyat Layer 2 but must pass through a Layer 3 device (e.g., a router or firewall).

Use Case:Typically used in enterprise networks, hotel networks, and campus networks to preventunwanted direct communicationbetween clients.

Thus, the statement iscorrect, and the answer isTRUE.

????Reference:Huawei HCIE Datacom Official Guide - Ethernet Port Isolation

In Huawei’sVXLAN implementation, the typical mapping betweenVNIs (VXLAN Network Identifiers)andBDs (Bridge Domains)is:

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

This allows properMAC learning and forwardingin the data plane for isolated tenant traffic.

Other mappings (N:1, 1:N, N:M) may be technically possible butnot recommendedor supported in most enterprise deployments.

Correct answer: B. 1:1

Comprehensive and Detailed Explanation:

BGP EVPN Type 3 routesare used forVXLAN ingress replicationandBUM (Broadcast, Unknown unicast, and Multicast) traffic forwarding.

✔Type 3 routes contain L2VNIs, not L3VNIs→(C is incorrect)

Key Functions of Type 3 Routes:

DistributeVTEP IP addressesto establish VXLAN tunnels.

IncludeL2VNIsfor mapping Layer 2 broadcast domains.

Used inIngress Replicationfor BUM traffic.

SinceType 3 routes do not carry L3VNIs, the correct answer isC.

????Reference:Huawei HCIE Datacom – BGP EVPN Type 3 Routes

BGP in Huawei SD-WAN

Huawei SD-WAN usesBGP (Border Gateway Protocol) as the primary routing protocolto exchange VPN routes between Customer Premises Equipment (CPEs) and the controller.

✅Why BGP is Used in SD-WAN?

Scalability: BGP can handle a large number of VPN routes.

Policy-Based Routing: BGP allowstraffic engineering and policy controlacross SD-WAN tunnels.

Multiprotocol Support: Huawei SD-WAN usesMP-BGP to exchange IPv4, IPv6, and VPNv4 routes.

Comprehensive and Detailed In-Depth Explanation:

Telemetry in a narrow senserefers specifically to thedevice-side telemetryprocess, which includes the following key modules:

Data generation (A):The device collects and generates telemetry data, such as performance metrics or operational statistics.

Data push (B):The deviceactively pushes the collected datato the configured destination (such as a collector or management system) using a data streaming protocol.

Data source (C):The entity on the device that generates or provides themonitored data.

Data subscription (D)isnot part of the device-side telemetry; it is related to themanagement system side, where users subscribe to specific telemetry data streams.

Therefore, the correct answers areA, B, C.

Understanding the Telemetry Output:

Dest-addr: 192.168.56.1→The destination IP address is 192.168.56.1.✅

Dest-name: Dest1→The destination group name is Dest1.✅

Protocol: gRPC→Data push uses the gRPC protocol.✅

Vpn-name: - (empty)→No VPN encapsulation is used.❌

Incorrect Answer Explanation:

❌C. "VPN encapsulation is used for data push"→Incorrect!

The Vpn-name field isempty, indicating thatVPN encapsulation is NOT enabled for telemetry data transport.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Destination and Data Push Methods

HCIE-Datacom Study Material – gRPC and Telemetry Data Streaming

Let’s analyze the scenario and each statement carefully based on OSPF path selection and BGP behavior in Huawei routers.

✅ Option A: The preferred path is R1–R3–R4.

According to the OSPF cost values:

R1–R3–R4: Cost = 1 + 1 = 2

R1–R2–R4: Cost = 2 + 2 = 4

OSPF chooses the lowest-cost path to reach a destination. Therefore, R1 will prefer the R1–R3–R4 path to reach 172.20.1.4/32.

Huawei Datacom Reference:

"OSPF selects routes based on the shortest path calculated using link costs. The router always selects the path with the lowest cost."

(Source: HCIE-Datacom Study Guide v3.0 – OSPF Path Selection, Chapter 5)

✅ Option B: If the stub router on-startup command is run on R3, packet loss occurs during the power-off process of R3 but no packet loss occurs during the startup process of R3.

When R3 is powered off, OSPF needs to reconverge, which causes temporary packet loss.

When R3 starts up, it will advertise itself as a stub router using the stub-router on-startup command. This tells OSPF not to use R3 as a transit path during the startup period, thus preventing traffic blackholing.

Huawei Datacom Reference:

"stub-router on-startup command prevents a newly started router from being used as a transit node by OSPF, allowing routing to remain stable during convergence."

(Source: HCIE-Datacom Study Guide v3.0 – OSPF Stub Router Functionality, Chapter 6.2)

❌ Option C: The preferred path is R1–R2–R4.

This is incorrect because the OSPF path cost via R2 is higher (4) than the cost via R3 (2).

❌ Option D: Packet loss occurs during both the power-off and startup processes of R3.

Incorrect. As explained above, when the stub-router on-startup command is used, packet loss is avoided during startup, but still occurs during power-off since the alternate path requires convergence.

In hot standby (active-active/load balancing) scenarios, Quick Session Backup is critical. This function ensures that session entries are immediately synchronized between firewalls to handle asymmetric traffic (where return traffic goes through a different firewall than the forward traffic).

Without it, the return packet may be dropped due to missing session information on the alternate firewall.

Exact Extract - HCIE-Datacom Security Module:

“When VGMP is in load balancing mode, quick session backup must be enabled to prevent traffic loss due to inconsistent forward and return paths.”