Huawei Updated H12-891_V1.0 Exam Questions and Answers by mikail

Understanding MPLS Forwarding Mechanism

MPLS (Multiprotocol Label Switching) is a high-performance forwarding mechanism that operates on two planes:

1️⃣Control Plane:

EstablishesLabel Switched Paths (LSPs)using protocols likeLDP (Label Distribution Protocol),RSVP-TE (Resource Reservation Protocol - Traffic Engineering), orBGP-LU (BGP Label Unicast).

Assignslabelsto packets based on routing policies.

2️⃣Data Plane (Forwarding Plane):

Uses aLabel Forwarding Information Base (LFIB)instead of traditional IP routing.

Packets areforwarded based on labels, not IP addresses.

Analysis of the Answer Choices

✅C. The system automatically assigns an ID to the upper-layer application that uses a tunnel. This ID is also called the tunnel ID.

Correct:MPLS assigns aTunnel IDto applications that utilize tunnels (e.g.,VPNs, MPLS-TE, or L2/L3 services).

This ID helpsdifferentiate between various tunnel applications, ensuring traffic follows the correct LSP.

❌A. After an IP packet enters an MPLS domain, the MPLS device forwards the packet based on FIB table queries.

Incorrect:MPLS routersdo NOT use the FIB (Forwarding Information Base)for forwarding once labels are assigned.

Instead, they useLFIB (Label Forwarding Information Base)to switch packets based on labels.

❌B. If the tunnel ID is 0x0, the MPLS forwarding process starts.

Incorrect:If theTunnel ID is 0x0, MPLSdoes NOT start; it means no label is assigned, and traditionalIP forwardingoccurs.

❌D. If the tunnel ID is not 0x0, the normal IP forwarding process starts.

Incorrect:If the Tunnel ID isnot0x0, MPLSforwards traffic using label switching, not IP forwarding.

On the2.4 GHzband, onlythree non-overlapping channelsexist:1, 6, and 11.

Inhigh-density WLAN scenarios, channels like1, 5, 9, and 13can be used withlower transmit powerto reduce co-channel interference — though they slightly overlap, they can work in dense deployments when managed properly.

On the5 GHzband, there are many non-overlapping channels. It’s recommended tostagger high and low channelsamong adjacent APs toavoid interference.

Correct answer: A. TRUE

Understanding Inter-AS MPLS L3VPN Option C

????MPLS L3VPN provides Layer 3 VPN services over an MPLS backboneby using BGP to exchange VPN routes.

????Inter-AS MPLS L3VPN Option C (Carrier-to-Carrier Model) works as follows:

ASBRs (Autonomous System Boundary Routers) exchangeVPNv4 routes using MP-BGP.

ASBRsdo NOT store VPN routing tables. Instead, theyadvertise labeled IPv4 routesto enable inter-AS forwarding.

How ASBR-PE2 Enables Inter-AS Communication?

✅VPNv4 Address Family (Answer A - Required)

Used to exchangeMPLS VPN routes between PE routers.

MP-BGP (Multiprotocol BGP) exchanges VPNv4 prefixesbetween ASBR-PE1 and ASBR-PE2.

✅Unicast BGP Address Family (Answer D - Required)

Required to exchangeIPv4 labeled routesbetween ASBRs.

EnsuresMPLS label forwarding between AS100 and AS200.

❌BGP-LS Address Family (Answer B - Not Required)

BGP-LS (BGP Link-State) is used for SDN controllersto learn topology information.

It isnot required for Inter-AS MPLS L3VPN.

❌VPN Instance Unicast Address Family (Answer C - Not Required)

This is used forPE-CE communicationbut isnot required between ASBRs.

Why is the Answer A, D?

✅VPNv4 routes enable inter-AS VPN communication.

✅IPv4 unicast routes are required for ASBR-PE2 to forward packets across AS boundaries.

Real-World Application:

Service Provider Networks:Used incarrier-to-carrier MPLS VPN deployments.

Enterprise WAN Interconnection:Enablesmulti-AS MPLS VPN connectivityfor large enterprises.

✅Reference:Huawei HCIE-Datacom Guide – Inter-AS MPLS L3VPN Option C (Carrier-to-Carrier Model)

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