Pass the Huawei HCIE-Datacom H12-891_V1.0 Questions and answers with ExamsMirror

GRE (Generic Routing Encapsulation) supports encapsulation of many protocol types:

Supports IPv4 and IPv6 unicast encapsulation — ✅

Does not support IPv6 broadcast encapsulation. GRE doesn’t natively handle multicast or broadcast IPv6 traffic well — ❌

It is a lightweight tunneling protocol and relatively easy to deploy, placing minimal overhead on devices — ✅

Correct answer: C. GRE can encapsulate IPv6 broadcast packets — is incorrect.

Huawei’s user access authentication configuration includes the following components:

AAA scheme: Defines how users are authenticated (local, RADIUS, HWTACACS, etc.).

Domain: Groups users and associates them with an AAA scheme.

Access profile: Defines access control rules like 802.1X, MAC, Portal, or multi-mode authentication.

Correct workflow:

Bind the authentication profile (which references the access profile) to the user access interface.

Not the other way around.

Incorrect statement:

D. It incorrectly states you bind the access profile to the authentication profile, when in fact, the authentication profile binds the access profile and is applied to the interface.

Correct answer: D

In YANG model syntax:

cpu-info can be a list node (✓)

cpu-infos can be a container node (✓)

The sampling path does follow the YANG model hierarchy (✓)

However, the prefix huawei-debug: indicates the YANG module name, not an actual data node. Therefore, debug is not necessarily the top node in the YANG hierarchy — it is a node under the huawei-debug namespace/module.

Exact Extract – Huawei Telemetry and YANG Modeling Guide:

“The format < module-name > : < data-node > is used in telemetry to indicate paths. The actual top-level node may differ from the module name.”

Comprehensive and Detailed In-Depth Explanation:

The gRPC-based telemetry protocol utilizes protocol 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

Explanation:

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

The file huawei-grpc-dialin.proto defines the gRPC service interfaces, message structures, and procedures for remote method invocation.

It is essential for establishing communication and invoking telemetry data collection.

Function: Manages dial-in and dial-out connections between the telemetry client and the server.

2. Telemetry Layer:

File: huawei-telemetry.proto

Explanation:

The telemetry layer is responsible for collecting, packaging, and exporting telemetry data.

The file huawei-telemetry.proto contains the data model used for telemetry reporting, including streaming data formats and telemetry messages.

It defines how the collected data is organized and transmitted.

Function: Provides a structured way to export telemetry data in real-time or batch mode.

3. Service Data Layer:

File: huawei-debug.proto

Explanation:

The service data layer contains data models related to diagnostics, debugging, and operational data.

The file huawei-debug.proto is used to collect debugging information from network devices.

This file is crucial for troubleshooting and monitoring the health of the system.

Function: Facilitates debugging and diagnostic telemetry data collection.

Why This Mapping Is Correct:

The mapping is based on the functional role of each layer and the purpose of each .proto file in the Huawei gRPC-based telemetry architecture.

Correctly identifying the file location is crucial for effective telemetry configuration and data collection.

In BGP4+ (used for IPv6 routing), the MP_REACH_NLRI attribute is used to advertise reachable routes. The Next Hop field must:

Contain a global unicast IPv6 address

Link-local addresses are not used in MP_REACH_NLRI because they are valid only on a local link and not suitable for inter-AS routing.

RFC 2545 (Multiprotocol Extensions for BGP-4) also states that the Next Hop must be a routable global address.

Therefore:

C. It must be a global unicast address — is correct.

The other options involving link-local addresses are incorrect.

Huawei’s SD-WAN solution offers a full suite of application optimization technologies, including:

Application identification: Uses DPI and traffic signatures to identify applications.

Intelligent traffic steering: Dynamically routes traffic based on application type and real-time link performance.

WAN optimization: Reduces latency, deduplicates traffic, and optimizes throughput for key apps.

QoS: Prioritizes critical applications and ensures bandwidth guarantees.

All listed options are part of the Huawei SD-WAN solution for optimizing user experience and application performance.

Correct answers: A, B, C, D

Understanding OSPF Neighbor States

OSPF (Open Shortest Path First) establishes neighbor relationships through several states:

1️⃣ Down: No Hello packets received.

2️⃣ Init: Router receives Hello packets but its own Router ID is missing in the received packets.

3️⃣ 2-Way: Routers see each other in Hello packets. (Stable state for non-DR/non-BDR routers).

4️⃣ ExStart: Routers start exchanging LSAs but may face MTU mismatches.

5️⃣ Exchange: Routers send Database Description (DBD) packets to synchronize link-state databases.

6️⃣ Loading: Routers exchange Link-State Requests (LSRs) & Updates (LSUs) to fully sync.

7️⃣ Full: Routers are fully synchronized.

Analysis of the Answer Choices

✅ A. For non-DR and non-BDR routers on an Ethernet link, the 2-Way state is acceptable.

Correct: Non-DR/Non-BDR routers remain in 2-Way state since they don’t need to form full adjacency.

✅ B. The Init state indicates that the router has received Hello packets from its neighbors, but the received Hello packets do not contain the OSPF RID of the receiving router.

Correct: If an OSPF router receives a Hello but does not see its own Router ID, it stays in the Init state.

✅ C. The ExStart state indicates that two neighbor routers have inconsistent MTUs or the same OSPF Router ID (RID).

Correct: If MTUs mismatch or RIDs conflict, the DBD exchange fails, causing routers to remain in ExStart state.

❌ D. The Attempt state indicates that the router does not send unicast Hello packets to configured neighbors.

Incorrect:

In Attempt state, routers send unicast Hello packets to manually configured neighbors (common in NBMA networks).

If no Hello responses are received, they remain in Attempt state, but they DO send Hellos.

Real-World Application

OSPF Troubleshooting: Identifying routers stuck in Init or ExStart states can point to MTU mismatches or neighbor misconfigurations.

NBMA Networks (Frame Relay, DMVPN): Manually configured neighbors may stay in Attempt state if Hello packets are lost.

✅ Reference: Huawei HCIE-Datacom Study Guide – OSPF Neighbor States & Troubleshooting

Comprehensive and Detailed In-Depth Explanation:

1. Portal Authentication:

Scenario: Guests who move frequently and use different types of terminals.

Explanation:

Portal authentication (also known as Web authentication) is commonly used in environments like Wi-Fi hotspots, hotels, and public areas.

Users are redirected to a login page where they enter credentials.

This method is flexible for guests and visitors who may frequently change locations or devices.

Use Case: Wi-Fi access for guests in a corporate environment.

2. MAC Address Authentication:

Scenario: Dumb terminals such as printers and fax machines.

Explanation:

MAC address authentication is useful for devices that do not support interactive authentication methods (like printers or IP phones).

It authenticates devices based on their MAC address without user intervention.

This method is suitable for static, non-user devices that are typically part of the local network.

Use Case: Ensuring that only authorized printers or IP phones connect to the network.

3. 802.1X Authentication:

Scenario: Office users in scenarios demanding high security.

Explanation:

802.1X is a port-based network access control protocol that authenticates users before allowing network access.

Typically used in wired or wireless LAN environments where high security is required.

It uses EAP (Extensible Authentication Protocol) methods and integrates with RADIUS servers.

Use Case: Corporate LAN environments with stringent security policies.

VXLAN Inter-Subnet Routing with Symmetric IRB

VXLAN supports inter-subnet routing using Integrated Routing and Bridging (IRB). In symmetric IRB, both ingress and egress VTEPs perform Layer 3 forwarding to ensure efficient packet forwarding across subnets.

✅ A. Both the ingress VTEP and egress VTEP forward packets based on the Layer 3 forwarding table.

In symmetric IRB, both ingress and egress VTEPs perform Layer 3 lookup and forwarding.

The ingress routes packets before encapsulating them in VXLAN, and the egress performs another Layer 3 lookup to determine final delivery.

✅ D. When VTEPs forward inter-subnet user communication packets, the VNI carried in the VXLAN header is the L3VNI.

L3VNI (Layer 3 VXLAN Network Identifier) is used for inter-subnet routing between VXLAN segments.

This statement confuses congestion management with congestion avoidance:

Congestion Management: Refers to techniques like PQ, CQ, WRR, etc., to schedule packets in queues — i.e., manage how packets are sent, not discarded.

Congestion Avoidance: Techniques like WRED are used to preemptively discard packets to avoid full queues — these do discard packets.

Hence, congestion management does NOT discard packets — it ' s about controlling transmission order and prioritization.

Correct answer: B. FALSE