Free Practice Questions for Huawei H12-891_V1.0 Exam

VXLAN Inter-Subnet Routing with Symmetric IRB

VXLAN supportsinter-subnet routingusingIntegrated Routing and Bridging (IRB). Insymmetric IRB, both ingress and egress VTEPs performLayer 3 forwardingto ensure efficient packet forwarding across subnets.

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

Insymmetric IRB, bothingress and egress VTEPs perform Layer 3 lookup and forwarding.

The ingressroutes packets before encapsulating them in VXLAN, and the egressperforms 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 forinter-subnet routingbetween VXLAN segments.

In OSPF (Open Shortest Path First), routers connected over broadcast networks (like Ethernet) elect aDesignated Router (DR)andBackup Designated Router (BDR).DR election is based on theinterface priority. If the priority is set to0, the routercannot become a DR or BDR.

Whenboth routers have a priority of 0,no DR or BDR will be elected, and since the election fails, the neighbor relationship between the two routers willnot advance beyond the 2-Way state. In this state, the routers acknowledge each other but do not exchange routing information in detail (as they only form full adjacency with the DR/BDR).

Therefore, the OSPF neighbor relationship remains in the2-Way state.

To configure an SR-MPLS TE tunnel based on OSPF, all four options are mandatory:

A. Configure the LSR ID – LSR ID is required as the unique identifier of the router in MPLS and TE.

B. Enable segment routing in the OSPF process view – Needed to advertise segment information (SID).

C. Enable the opaque capability – Opaque LSAs are used to carry SR and TE information in OSPF.

D. Enable MPLS TE in the OSPF process view – Ensures that TE-related attributes (e.g., bandwidth) are advertised in OSPF LSAs.

Exact Extract - Huawei HCIE-Datacom SR-MPLS TE Configuration Guide:

“To support SR-MPLS TE over OSPF, it is necessary to configure the LSR ID, enable SR and MPLS TE capabilities in OSPF, and activate the OSPF opaque capability for carrying TE and SR attributes.”

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

When port security is enabled and the maximum number of learned MAC addresses is reached, the switch can trigger multiple security actions depending on configuration:

Discard packets with unknown source MACs

Generate alarms

Shut down the port (set to error-down)

Do all the above combined (default behavior)

The most comprehensive and commonly configured behavior is error-down + alarm generation, which corresponds to Option D.

Exact Extract - Huawei HCIE-Datacom Switching Guide:

“When the MAC address limit is reached on a port with port security enabled, the system can generate alarms and set the port to error-down state based on security policies.”

NAFTIR (Network Address Flow Traffic Incoming Rate) policingis a traffic control mechanism that can only be applied toinboundtraffic.

Purpose:

Monitorsandlimitsthe traffic entering a network device.

Preventsupstream devices fromoverloadingthe network with excessive data.

Key Fact:Outbound policing requires different mechanisms likeQoS shapingortraffic scheduling.

✅Reference:Huawei HCIE-Datacom Study Guide - Traffic Policing and Shaping

In OSPFv3 (used for IPv6), Link LSAs (Type 8) are not advertised throughout the entire area. Instead, they are only advertised on a specific link (i.e., the local link). This differs from OSPFv2, where LSAs like Type 1 or Type 2 are advertised across the area.

Exact Extract - Huawei HCIE-Datacom V1.0 Courseware - Chapter: OSPFv3 Operation

“Link LSAs are generated by routers for each attached link and sent only on that link, not flooded throughout the area.”

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

Huawei AR routers used as egress gateways in CloudCampus solutions support multiple onboarding and deployment methods, including:

DHCP Option 148-based auto-deployment

Web-based management

CLI-based deployment and configuration (also supported)

So, the statement is incorrect—CLI-based deployment is supported.

Exact Extract - Huawei CloudCampus AR Router Deployment Guide:

“AR series routers support multiple deployment methods including CLI, DHCP Option 148, and web-based registration.”

A screenshot of a computer AI-generated content may be incorrect.

InOSPFv3, each LSA type has adefined flooding scope:

Link-LSA (Type 8)

Advertisedonly on the local link

Contains router’s link-local address and prefixes

Scope:Within the local link scope✅

AS-External-LSA (Type 5)

Used to advertiseexternal routes from outside the AS

Flooded across theentire autonomous system, except stub/NSSA areas

Scope:Within an AS✅

Network-LSA (Type 2)

Generated by theDesignated Router (DR)

Describes all routers on a broadcast or NBMA segment

Floodedwithin the originating area

Scope:Within an area✅

Correct Mappings:

Link LSA→Within the local link scope

AS-External-LSA→Within an AS

Network-LSA→Within an area