H12-891_V1.0 Exam Dumps - Huawei HCIE-Datacom Questions and Answers

OSPF (Open Shortest Path First) Router-LSA (Type 1 LSA) describes all directly connected OSPF links of a router and their types. The following link types can appear in a Router-LSA:

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

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

Stub Network (StubNet) (D) – Represents a network 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

Congestion Avoidance in Networking

Congestion avoidance mechanisms prevent packet loss and delay by managing queues before congestion occurs.

Common Congestion Avoidance Techniques:

Weighted Random Early Detection (WRED) – Randomly drops low-priority packets before congestion builds up.

Explicit Congestion Notification (ECN) – Marks packets instead of dropping them to signal congestion.

Queue Management – Techniques like priority queuing (PQ) and weighted fair queuing (WFQ) help prevent congestion.

Reference from Huawei HCIE-Datacom Documentation:

Huawei QoS Configuration Guide – Congestion Avoidance Technologies

HCIE-Datacom Study Material – Traffic Management and Queue Optimization

Dynamic VLAN Authorization in Huawei CloudCampus

Dynamic VLAN assignment allows users to be placed into specific VLANs based on authentication methods, ensuring security and network segmentation.

Correct Explanations:

✅ A. Wired users using 802.1X authentication receive VLAN assignments dynamically.

After authentication, the access control system (e.g., iMaster NCE-Campus) assigns VLANs dynamically.

✅ C. Wireless users using 802.1X authentication also receive VLAN assignments.

Similar to wired users, wireless 802.1X authentication allows dynamic VLAN assignment via the RADIUS server.

✅ D. Wired users using MAC authentication can receive VLAN assignments.

If a user does not support 802.1X, MAC authentication can still be used to assign VLANs dynamically.

Incorrect Statement Explanation:

❌ B. When wireless users pass Portal authentication, they join the authorization VLANs delivered to edge nodes.

Wrong! In Portal authentication, VLAN assignment is not dynamically delivered because Portal authentication typically applies access policies, not VLAN changes.

Dynamic VLAN assignment is mainly used with 802.1X or MAC authentication.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Configuration Guide – Dynamic VLAN Assignment and Authentication

HCIE-Datacom Training Material – VLAN Authorization in Virtualized Campus Networks

Understanding HTTP/1.1 Response Headers

???? What is an HTTP Response?

When a web server responds to an HTTP request, it sends an HTTP response message.

The response contains headers, a status line, and a response body.

Elements of an HTTP Response Header:

✅ A. Status Code → Correct

Indicates the response status (e.g., 200 OK, 404 Not Found).

✅ B. Reason Phrase → Correct

Provides a human-readable explanation of the status code (e.g., OK, Not Found).

✅ C. Protocol Version → Correct

Specifies which HTTP version is being used (e.g., HTTP/1.1).

❌ D. Response Method → Incorrect

The HTTP method (GET, POST, etc.) is part of the request, not the response.

Understanding L3VPN over SRv6 BE Networks

???? What is L3VPN over SRv6?

Layer 3 VPN (L3VPN) allows multiple private routing domains to operate over a shared service provider backbone.

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

Best Effort (BE) mode means that no 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 for VPN routing at PE2 (End.DT4 function).

Step-by-Step Route Learning Process:

1️⃣ PE1 advertises the 192.168.1.0/24 VPN route to PE2 using iBGP VPNv4.2️⃣ PE2 receives the route with next-hop 2001:DB8:1::1 (PE1).3️⃣ PE2 installs the route with the SRv6 Prefix-SID FC00:2::1:79 (End.DT4).4️⃣ The 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 that PE2 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:

The import-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: Uses SRv6 to replace MPLS in large-scale VPN deployments.

5G Transport Networks: Implements SRv6 L3VPN for high-speed, low-latency services.

Portal Authentication vs. MAC Authentication

✅ Portal Authentication

Used in high-mobility environments (e.g., shopping malls, hotels, and public Wi-Fi hotspots).

Users authenticate via a web portal before gaining network access.

Supports multiple device types (smartphones, laptops, tablets, etc.).

✅ MAC Address Authentication

Used for dumb devices that cannot perform interactive authentication (e.g., printers, IP phones, cameras).

The network authenticates devices based on their MAC addresses automatically.

Often used in enterprise LANs to ensure unattended devices get network access securely.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Authentication Guide – Portal and MAC Authentication

HCIE-Datacom Training Material – Access Control Mechanisms

Comprehensive and Detailed Explanation:

R2 is an Area Border Router (ABR), meaning it connects multiple OSPF areas (Area 0 and Area 1).

ABRs generate Router-LSAs for each area they belong to.

Since R2 is part of both Area 0 and Area 1, it must generate Router-LSAs (Type 1) for both areas.

R2 does not forward Router-LSAs between areas; instead, it generates Summary LSAs (Type 3) to exchange routing information between areas.

Thus, the correct answer is D.

???? Reference: Huawei HCIE Datacom – OSPF LSA Types and ABR Behavior

WRED (Weighted Random Early Detection) helps prevent congestion by randomly discarding packets before buffers are full.

Drop Probability Behavior:

Below lower threshold = 0% drop (packets pass normally).

Between lower & upper threshold = Progressively increasing drop probability.

Above upper threshold = 100% drop (probability = 1).

✅ Reference: Huawei HCIE-Datacom Guide - WRED Mechanism

Understanding Prefix Lists

IP Prefix-Lists are used for filtering BGP routes and controlling route advertisement & redistribution.

The command ip ip-prefix TEST permit 10.0.0.0 24 less-equal 30 means:

Matches prefix 10.0.0.0/24 exactly.

Matches any subnet of 10.0.0.0/24 with a prefix length between 24 and 30.

Analysis of Routes:

✅ 10.0.0.0/24 → Matches exactly.

✅ 10.0.0.1/30 → Falls within 10.0.0.0/24 & length ≤30.

❌ 10.0.1.0/24 → Not within 10.0.0.0/24 range.

❌ 10.0.2.0/24 → Not within 10.0.0.0/24 range.

Real-World Use Case:

BGP route filtering: Only allows 10.0.0.0/24 and its subnets (up to /30).

Prevents unintended route propagation in large-scale networks.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Prefix-Lists

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Comprehensive and Detailed Explanation:

✔ All four egress modes are supported in Huawei CloudCampus Virtualized Fabric to provide flexibility in connecting external networks.

✔ Modes Explained:✅ Layer 3 Shared Egress → Multiple VNs share a single Layer 3 gateway for external communication.✅ Layer 2 Shared Egress → Multiple VNs share the same Layer 2 link to the external network.✅ Layer 3 Exclusive Egress → Each VN has its own separate Layer 3 gateway to external networks.✅ Layer 2 Exclusive Egress → Each VN has its own dedicated Layer 2 link for external connectivity.

???? Reference: Huawei HCIE Datacom – CloudCampus Fabric Egress Modes