H12-891_V1.0 Huawei HCIE-Datacom V1.0 Free Practice Exam Questions (2025 Updated)

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

InSR-MPLS (Segment Routing over MPLS),prefix SID conflictsmay occur if multiple prefixes are assigned the same SID or vice versa.

Conflict resolution principle (Huawei standard):

When there aremultiple SIDs for the same prefix, theSID with the lowest value wins.

Whenthe same SID is assigned to multiple prefixes, theprefix with the smallest addresswins.

Apply to this case:

Conflict: Two entries for1.1.1.1/32withSID 2 and SID 1.

SID 1 is lower, so1.1.1.1/32 → SID 1is selected.

Correct answer: D. 1.1.1.1/32 → SID 1

Comprehensive and Detailed In-Depth Explanation:

In the Label Distribution Protocol (LDP) session establishment process, theInitialization messageis sent by the initiator to propose parameters for the session. If the responder finds that the proposed parameters are not acceptable, it responds with anError Notification Message. This message indicates that the session could not be established due to incompatible or incorrect parameters.

TheError Notification Messagetypically includes details about why the session could not be established, such as parameter mismatch or unsupported features. If the parameters are acceptable, the responder would instead reply with aKeepalive Messageto maintain the session.

FEC (Forwarding Equivalence Class) in MPLS is a group of packets that are forwarded in the same manner. MPLS can classify packets into FECs based on factors such as:

Destination IP address

Source address

CoS (Class of Service)

Application type

However, Fragment Offset, which is part of the IP header used for IP fragmentation, is not used in FEC classification. Fragment offset is more relevant to how IP packets are reconstructed and not suitable or used as a classification standard for forwarding decisions in MPLS.

Exact Extract - Huawei HCIE-Datacom V1.0 MPLS Chapter:

“FEC classification may be based on various parameters including destination address, source address, and even CoS values. However, fragment offset is not used as an FEC criterion, as MPLS forwarding occurs before IP reassembly.”

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

IS-IS was originally designed for IPv4, but extensions via TLVs (Type-Length-Value) allow it to support IPv6. These are referred to as New IS-IS TLVs, including TLV 236 (IPv6 Reachability), TLV 232 (IPv6 Interface Address), etc. These TLVs are crucial for IPv6 route computation within IS-IS.

Exact Extract - HCIE-Datacom Guide – IPv6 Routing Protocols Chapter

“IS-IS uses new TLVs such as TLV 236 and TLV 232 to carry IPv6 prefix and interface address information. These TLVs are essential to enable IPv6 route calculation.”

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.

Comprehensive and Detailed In-Depth Explanation:

WhenIS-ISis used as theIGP (Interior Gateway Protocol)to advertiseSegment Routing (SR) SIDs, theLevel-2 (L2) routeradvertisesnode SIDs globally across the entire IS-IS domain, not just within a single area.

Level-1 (L1) routersonly advertise within the local area, butL2 routersdistribute information across multiple areas, enabling inter-area reachability.

Therefore, the statement isFALSE.