Huawei H12-891_V1.0 - HCIE-Datacom V1.0

Comprehensive and Detailed Explanation:

✔iMaster NCE-WANis thecentralized SD-WAN controllerthat:

Manages SD-WAN network devices(CPEs, routers).

Optimizes traffic steeringusing AI-driven policies.

Enables automation, security, and analytics.

Thus, the statement isTRUE.

📖Reference:Huawei HCIE Datacom – SD-WAN Architecture

Comprehensive and Detailed Explanation:

✔802.1X authenticationsupportsmultiple logout mechanismsbased on network conditions and security policies.

✔Correct Logout Modes:

✅(A) Authentication Server Logout→ The RADIUS server canterminatea session.

✅(B) Manual Logout→ Users candisconnect manually.

✅(C) Access Device Logout→ The switch/WLAN controller canenforce logouts(e.g., if inactivity is detected).

✔Why Not (D)?

❌(D) Accounting Server Logout→ Theaccounting server tracks session usagebutdoes not enforce logouts.

📖Reference:Huawei HCIE Datacom – 802.1X Authentication & Session Termination

The Loopback interface is not advertised by default in IS-IS, unless a specific command is used (like network entity with loopback settings or enabling it manually). In this case, the GE0/0/0 and GE0/0/1 interfaces are both UP, and have IS-IS L1/L2 enabled. These two interfaces qualify to advertise IS-IS routes.

Exact Extract - Huawei HCIE-Datacom V1.0 IS-IS Chapter

“By default, only physical interfaces in UP state and configured with IS-IS (L1, L2, or L1/L2) participate in IS-IS. Loopback interfaces must be explicitly advertised using route import policies.”

OSPFv3 (used for IPv6) usesIPv6 multicast addressesfor communication between routers:

FF02::5— All OSPF routers.

FF02::6— All OSPF Designated Routers (DRs) and Backup Designated Routers (BDRs).

FF08::x— These are used for organization-local scope, which isnotapplicable to standard OSPFv3 operation.

Therefore:

C. All OSPF routers use FF02::5— Correct

D. The DR uses FF02::6— Correct

A and B (FF08::x)— Incorrect. These addresses are not used by OSPFv3 in this context.

Correct answers: C and D

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.

Understanding L3VPN over SRv6 BE Networks

🔹What is L3VPN over SRv6?

Layer 3 VPN (L3VPN) allowsmultiple private routing domainsto operate over a shared service provider backbone.

SRv6 (Segment Routing over IPv6) replaces traditionalMPLS labels with IPv6 Segment Identifiers (SIDs).

Best Effort (BE)mode means thatno explicit Traffic Engineering (TE) constraints are applied.

How Routing Works in This Scenario

Key Components in the Network:

PE1 & PE2 (Provider Edge routers): Connect customer networks (CE1 & CE2).

P Router (Core Router): Provides transit between PE routers over SRv6.

SRv6 SID FC00:2::1:79: Used forVPN routing at PE2(End.DT4 function).

Step-by-Step Route Learning Process:

1️⃣PE1 advertises the 192.168.1.0/24 VPN route to PE2 using iBGP VPNv4.

2️⃣PE2 receives the route with next-hop 2001:DB8:1::1 (PE1).

3️⃣PE2 installs the route with the SRv6 Prefix-SID FC00:2::1:79 (End.DT4).

4️⃣The route is imported into the VRF using the import-route command.

Analysis of Each Answer Choice

✅A. An IBGP peer relationship is established between PE2 and PE1, and PE2 learns the route to 192.168.1.0/24 over an IBGP peer relationship.

Correct:The routing table output confirms thatPE2 receives the route via iBGP from PE1.

✅B. The instruction type corresponding to FC00:2::1:79 is End.DT4.

Correct:

End.DT4 is an SRv6 function that represents a Layer 3 VPN endpoint (VRF routing).

PE2 uses End.DT4 to process VPN traffic for 192.168.1.0/24.

✅C. PE2 imports the route 192.168.1.0/24 through the import-route command.

Correct:

Theimport-route command allows BGP-learned routes to be added to the local routing table (VRF).

❌D. The router ID of the BGP process on the P router is 1.0.0.6. (Incorrect Statement)

Incorrect:

The P router is a transit router and does NOT run BGP for VPNv4 routes.

The router ID of PE2 is 1.0.0.11, and the route originator is 1.0.0.2 (likely PE1).

P routers in an SRv6 BE network do NOT need BGP router IDs.

Final Answer: D (The router ID of the BGP process on the P is 1.0.0.6.)

✅Reference:Huawei HCIE-Datacom Guide – SRv6 L3VPN Routing and End.DT4 Function

Real-World Application:

Service Provider Networks:UsesSRv6 to replace MPLS in large-scale VPN deployments.

5G Transport Networks:ImplementsSRv6 L3VPN for high-speed, low-latency services.

In Huawei'sSRv6 instruction namingsystem, each letter keyword represents a specific forwarding behavior:

X (Cross): Forwards packets viaspecified Layer 3 interfaces→✅

M (MAC): SearchesLayer 2 forwarding tableforbroadcast/multicast,not unicast→❌

V (VPN): Searches theVPN routing table (VRF)for forwarding →✅

T (Table): Searches aspecific routing table (e.g., user-defined)→✅

Correct answers: A, C, D

Comprehensive and Detailed Explanation:

✔SR Policies are dynamically computed and delivered by the SDN controllerin an SR-MPLS or SRv6 network.

✔Correct Statements:

✅(A)NETCONFis used fordelivering configurationslikerouting policies and service interfaces.

✅(B)BGP-LS (Link-State)is used tocollect topologyandcompute SR Policies.

✅(D)BGP IPv6 SR Policydistributes SR policy attributes likecolor, headend, and endpoints.

✔Why Is (C) Incorrect?

❌(C) The controller does not use telemetry to deliver SID entries—telemetry is used forreal-time monitoring, not path computation.

📖Reference:Huawei HCIE Datacom – SR Policy and Controller-Based Path Computation

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.”

Comprehensive and Detailed In-Depth Explanation:

The IP prefix list configuration:

ip ip-prefix TEST permit 10.0.0.0 24 less-equal 30

10.0.0.0/24: Matches because it falls within the10.0.0.0/24prefix with thesame prefix length (24).

10.0.1.0/24: Matches because it also falls within the/24network range.

10.0.2.0/24: Matches for the same reason as the above.

10.0.0.1/30: Matches because it falls within the/24 prefixand itssubnet length (30)is within theless-equal 30range.

The prefix list permits any route that falls within the10.0.0.0/24network with asubnet mask ranging from /24 to /30. Therefore,all given routes are matched.