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

6PE (IPv6 Provider Edge over MPLS) vs. 6VPE (IPv6 VPN Provider Edge over MPLS VPNs)

6PE (IPv6 over MPLS without VPNs):

Uses global IPv6 routingover MPLS.

No VPN instances (VRFs) are created on PEs.

IPv6 addresses cannot be reusedacross different CEs because all traffic is routed using a single global table.

6VPE (IPv6 over MPLS with VPNs):

Uses MPLS VPN (VRF instances) to provide IPv6 VPN services.

VPN instances (VRFs) are created on PEsto separate customer networks.

IPv6 addresses of CEs can be reusedin different VPN instances because each VRF maintains separate routing tables.

Correct Answer Explanation:

✅C. In 6VPE networking, IPv6 addresses of a CE can be reused.

Sinceeach VPN instance (VRF) maintains its own IPv6 routing table, IPv6 addresses of CEscan be reused across different VPNs.

Incorrect Answer Explanations:

❌A. In 6PE networking, VPN instances need to be created on PEs.

Wrong!6PEdoes not use VPN instances (VRFs); it relies on a global IPv6 routing table.

❌B. In 6PE networking, IPv6 addresses of a CE can be reused.

Wrong!Since 6PE uses asingle IPv6 global routing table, IPv6 addressescannot be reused.

❌D. In 6VPE networking, no VPN instance needs to be created on PEs.

Wrong!6VPErequires VPN instances (VRFs) on PEsto separate customer traffic.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – 6PE and 6VPE Deployment

HCIE-Datacom Training Material – IPv6 MPLS Solutions

Understanding User Authentication Points in a Network

Authentication pointscan be deployed at different network layersbased on security and scalability needs:

✅Access Layer Authentication:

Ensureshigh security & granular control(user-level authentication).

Preferred inhigh-security enterprise networks.

✅Aggregation or Core Layer Authentication:

Reduces authentication overheadbutprovides less granular control.

Suitable forlarge-scale networkswhere authentication load needs to be balanced.

Analysis of the Answer Choices:

✅A. Deploying user authentication points at the access layer achieves granular permission management and high network security.

Correct:Providesfine-grained control per userand prevents unauthorized access.

✅B. Moving user authentication points from the access layer to the aggregation or core layer greatly reduces the number of user authentication points, thereby effectively mitigating the pressure on the AAA server.

Correct:Fewer authentication points meanless load on the AAA server.

✅C. Deploying user authentication points at the access layer has both advantages and disadvantages when compared to doing so at the aggregation or core layer. Policy association can be applied if user authentication points are deployed at the access layer.

Correct:Policy-based authentication isbest applied at the access layerforgranular control.

❌D. When user authentication points are moved from the access layer to the aggregation layer, MAC address authentication for users may fail.

Incorrect:MAC authentication worksat both layers, butpolicy adjustmentsmay be needed.

✅Reference:Huawei HCIE-Datacom Guide – User Authentication Strategies in Enterprise Networks

Before performing anetwork cutover (migration or upgrade), it is essential to collectbaseline datato ensure that services operate normally before and after the change.

Importance of Pre-Cutover Information Collection:

Identifies Network Baseline– Helps comparepre-cutover and post-cutover performance.

Detects Hidden Issues– Ensures that no existing network issues interfere with the cutover process.

Prevents Service Interruptions– Ensures all dependent services are accounted for.

Provides Rollback Plan– If issues arise, administrators canrestore previous configurations.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Network Change Management Guide – Pre-Cutover & Post-Cutover Best Practices

HCIE-Datacom Training Material – Service Assurance & Risk Analysis

VXLAN tunnel configuration, you donot use a control planelike BGP EVPN. Instead, youmanually configureall necessary forwarding parameters, including:VNI (VXLAN Network Identifier): Identifies the VXLAN segment.VTEP IP Address: The remote tunnel endpoint.Ingress Replication List: Required for multicast emulation (flooding/BUM traffic) in the absence of a multicast control plane.Whenconfiguring statically, theVNIis essential to map Layer 2/3 services to the correct VXLAN segment.Thus, the correct word to complete the sentence is:VNICorrect answer: VNI

OSPF (Open Shortest Path First) Router-LSA (Type 1 LSA)describesall directly connected OSPF linksof a router and their types. Thefollowing link types can appear in a Router-LSA:

Point-to-Point (P-2-P) (B)– Represents adirect connection between two routers.

Virtual Link (Vlink) (C)– Used toconnect an area to the backbone (Area 0)when a direct connection is unavailable.

Stub Network (StubNet) (D)– Represents anetwork with only one exit point(e.g., a loopback interface or passive interface).

Incorrect Option:

TransNet (A) – Incorrect!

Transit networks appear in Network LSAs (Type 2), not Router LSAs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPF Configuration Guide – Router-LSAs and Link Types

HCIE-Datacom Training Material – OSPF LSAs and Topology Advertisement

InMPLS LDP (Label Distribution Protocol), label retention modes control how labels are stored in theLabel Forwarding Information Base (LFIB).

DU Label Advertisement Mode (Downstream Unsolicited):

Labels areadvertised to all LDP peers without a request.

The receiving routerdecides which label to usefor forwarding.

Liberal vs. Conservative Label Retention:

✅Liberal Label Retention Mode (Correct Answer)

All received labels from all LDP peers are stored.

Even if apeer is not the optimal next hop, its label is retained.

Allowsfaster convergenceduring failures.

❌Conservative Label Retention Mode

Only the label from the best next-hop peer is stored.

Reduces memory usage but can slow down convergence in case of failure.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS LDP Configuration Guide – Liberal vs. Conservative Label Retention

HCIE-Datacom Training Material – Label Advertisement in MPLS Networks

Comprehensive and Detailed In-Depth Explanation:

The telemetry protocol stack is structured as follows:

Communication layer (A): Manages data transmission between the telemetry client (device) and the server.

Transport layer (B): Uses protocols such as gRPC, HTTP/2, or TCP to transmit telemetry data.

Data encoding layer (C): Encodes data using formats like JSON, Protobuf, or XML.

The Data analysis layer (D) is not part of the telemetry protocol stack itself.

Data analysis typically occurs after the data has been collected and received on the server or collector.

Telemetry focuses on data collection, encoding, transport, and transmission, not on analysis.

Therefore, the correct answer is D.

Comprehensive and Detailed In-Depth Explanation:

The statement A is incorrect because enabling DHCP snooping in the VLAN view only takes effect on interfaces within that specific VLAN that have DHCP snooping configured. It does not automatically apply to all interfaces of the device. Each interface within the VLAN must individually be configured or marked as trusted/untrusted.

B: Correct, as DHCP snooping, when enabled globally without any additional specifications, defaults to processing DHCPv4 messages.

C: Correct, as DHCP snooping can protect against DHCP spoofing attacks by marking interfaces as trusted or untrusted.

D: Correct, enabling DHCP snooping on an interface means it will monitor all DHCP messages on that specific interface.

Comprehensive and Detailed In-Depth Explanation:

The Strict Priority (SP) scheduling algorithm always gives preference to high-priority queues.

A: Correct. SP scheduling may lead to queue starvation because low-priority queues might never get serviced if high-priority traffic is constant.

B: Correct. SP always schedules the highest-priority queue first.

C: Correct. Among multiple low-priority queues, if SP is combined with FIFO (First In, First Out), packets that arrive first are forwarded first.

D: Incorrect. The SP algorithm does not guarantee minimum bandwidth for lower-priority queues. It prioritizes high-priority queues regardless of bandwidth configuration, which can lead to starvation of lower-priority traffic. To ensure minimum bandwidth, a Weighted Fair Queuing (WFQ) or CBWFQ (Class-Based Weighted Fair Queuing) algorithm would be more suitable.