In OSPF (Open Shortest Path First), routers connected over broadcast networks (like Ethernet) elect a Designated Router (DR) and Backup Designated Router (BDR). DR election is based on the interface priority. If the priority is set to 0, the router cannot become a DR or BDR.

When both 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 will not 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 the 2-Way state.

Comprehensive and Detailed Explanation:

✔ SRv6 Locator and Segment Structure:

The SRv6 Locator is 2001:DB8:ABCD::/64 → This defines the segment routing namespace for this node. ✅

Dynamic Segment (SID) = 32 bits → Defined dynamically per segment. ✅

Args Field = 32 bits → Used for function arguments. ✅

❌ (B) Incorrect → Static segments are NOT explicitly defined as 32-bit fields in Huawei SRv6.

???? Reference: Huawei HCIE Datacom – SRv6 Locator and SID Structure

BGP EVPN in VXLAN Tunneling

✅ A. MP_REACH_NLRI is used to carry routing information.

MP_REACH_NLRI (Multiprotocol Reachable Network Layer Reachability Information) is used in BGP updates to carry VXLAN reachability information.

✅ B. Several BGP EVPN routes are defined through BGP extension.

BGP EVPN introduces multiple route types, such as Type 2 (MAC/IP Advertisement), Type 3 (Inclusive Multicast), and Type 5 (IP Prefix Advertisement).

✅ D. MP_REACH_NLRI is used to carry the RT.

RT (Route Target) defines route import/export policies in VPN environments.

MP_REACH_NLRI carries the RT attribute in BGP EVPN updates.

❌ Incorrect Answer:

❌ C. MP_REACH_NLRI is used to carry the RD.

Wrong! The Route Distinguisher (RD) is carried inside BGP attributes, but not in MP_REACH_NLRI.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – BGP EVPN Route Types

HCIE-Datacom Training Material – VXLAN Dynamic Tunnel Establishment

Understanding MPLS Label Retention Modes

In MPLS (Multiprotocol Label Switching), a Label Switching Router (LSR) can operate in one of two label retention modes:

1️⃣ Liberal Label Retention Mode (LLRM)

Stores all labels received from neighbors, even if they are not immediately used.

Advantage: Fast convergence during link failures.

Disadvantage: Consumes more memory & label space.

2️⃣ Conservative Label Retention Mode (CLRM)

Only keeps labels for the best next-hop path.

Advantage: Saves memory & label space.

Disadvantage: Slower convergence when topology changes.

Why are C and D Correct?

✅ C. An LSR reserves all labels distributed by its neighbor.

Correct: In Liberal Mode, the router accepts and stores all labels received, even for non-best paths.

✅ D. The liberal mode requires more memory and label space.

Correct: Since the router keeps all labels, it requires higher memory & storage.

Why are A and B Incorrect?

❌ A. An LSR retains labels from a neighboring LSR only when the neighbor is its next hop.

Incorrect: This describes Conservative Mode, not Liberal Mode.

❌ B. This label retention mode saves memory and label space.

Incorrect: Liberal Mode consumes more memory, not less.

Real-World Application

Liberal Mode is used in large-scale MPLS networks where fast failover is critical.

Conservative Mode is preferred in memory-constrained environments.

✅ Reference: Huawei HCIE-Datacom Study Guide – MPLS Label Retention Modes

Comprehensive and Detailed In-Depth Explanation:

A. When planning paths based on bandwidth: Correct. The available bandwidth of each interface must be set in advance to allow path planning based on bandwidth requirements.

B. When planning paths based on delay: Correct. To plan paths considering delay, you need to deploy TWAMP (Two-Way Active Measurement Protocol) or iFIT (Intelligent Flow Information Telemetry) to measure the real-time delay on network links.

C. If the controller plans SR-MPLS Policy paths: Incorrect. The controller can plan primary, backup, and load-balanced paths, enabling traffic distribution across multiple paths.

D. Statically planned SR-MPLS Policy paths: Correct. You can manually configure load balancing for the primary path when planning the SR-MPLS Policy path statically.

In the Huawei SD-WAN solution, LAN-side devices (such as CPEs and aggregation routers) use various routing protocols to connect to Layer 3 networks and exchange routes dynamically. The supported protocols include:

✅ A. IS-IS (Intermediate System to Intermediate System)

A link-state protocol often used in large enterprise networks for fast convergence and scalability.

✅ B. OSPF (Open Shortest Path First)

A widely used dynamic routing protocol for intra-domain (LAN) connectivity.

Commonly used in enterprise networks to connect SD-WAN edge routers to LAN networks.

✅ C. BGP (Border Gateway Protocol)

BGP is primarily used for WAN and internet connectivity, but it can also be used inside large enterprise networks for LAN-side routing.

BGP enables inter-domain routing and policy-based route control.

✅ D. RIP (Routing Information Protocol)

A legacy distance-vector protocol still supported in some networks for basic LAN routing.

Less preferred due to slow convergence and hop-count limitations.

Reference from Huawei HCIE-Datacom Documentation:

Huawei SD-WAN Deployment Guide – LAN-Side Routing Protocols

HCIE-Datacom Training Material – Routing Configuration in SD-WAN

Understanding VXLAN and ARP Suppression in BGP EVPN

VXLAN (Virtual Extensible LAN) is used to extend Layer 2 networks over Layer 3 infrastructure.

VXLAN uses VTEPs (VXLAN Tunnel Endpoints) to encapsulate and forward Layer 2 traffic.

BGP EVPN (Ethernet VPN) is used for MAC/IP address learning and distribution across VXLAN networks.

How ARP Request Forwarding Works in This Scenario?

1️⃣ ARP Broadcast Suppression Enabled (VXLAN Optimized Forwarding)

Since ARP broadcast suppression is enabled on VTEP1, the ARP request is not flooded.

Instead, VTEP1 checks its EVPN learned database to find PC2’s MAC address (MAC C).

2️⃣ VTEP1 Encapsulates the ARP Request

VTEP1 encapsulates the ARP request in a VXLAN packet and sends it to VTEP2.

The original ARP frame inside the VXLAN tunnel still has:

Source MAC: MAC A (PC1 ' s MAC)

Destination MAC: MAC C (PC2 ' s MAC, learned via EVPN)

3️⃣ VXLAN Outer Headers

The outer VXLAN header uses:

Source IP: 1.1.1.1 (VTEP1)

Destination IP: 2.2.2.2 (VTEP2)

VNI (VXLAN Network Identifier): 200 (BD 20)

4️⃣ VTEP2 Receives and Forwards the ARP Request

VTEP2 decapsulates the VXLAN packet and forwards the original ARP request to PC2 (MAC C).

This ensures that only the intended receiver (PC2) gets the ARP request, preventing unnecessary broadcast flooding.

Why the Answer is MAC C?

✅ B. MAC C is Correct

The destination MAC of the inner data frame is PC2’s MAC (MAC C).

This is because VTEP1 forwards the ARP request directly to VTEP2, which then forwards it to PC2.

Why Other Answers Are Incorrect?

❌ A. MAC B (Incorrect)

MAC B is VTEP1’s MAC address, which is used in the outer VXLAN header, not in the inner Ethernet frame.

❌ C. MAC A (Incorrect)

MAC A is the source MAC of the ARP request (PC1), not the destination.

❌ D. MAC D (Incorrect)

MAC D is not mentioned in the topology, so it is irrelevant.

???? Reference: Huawei HCIE Datacom – VXLAN BGP EVPN and ARP Suppression

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.”

The MPLS header consists of:

Label (20 bits) – Label value used for forwarding.

EXP (3 bits) – QoS field (Class of Service).

S bit (1 bit) – Bottom-of-Stack indicator.

TTL (8 bits) – Time-to-Live, similar to the TTL field in the IP header.

Function of TTL in MPLS:

It is used to prevent infinite loops.

Every LSR decrements the TTL by 1.

When TTL reaches 0, the packet is discarded.

This mirrors the behavior of IP TTL and ensures loop prevention in MPLS networks.

Correct answer: D. This field is used to prevent packet forwarding loops, similar to the TTL field in an IP header.

Understanding iMaster NCE-Campus Terminal Identification

Huawei ' s iMaster NCE-Campus is an AI-driven network management platform for campus networks.

???? Terminal Identification Features in iMaster NCE-Campus

Identifies device type (e.g., Laptop, Mobile, IoT device).

Detects Operating System (Windows, Linux, Android, iOS).

Determines manufacturer information (Huawei, Apple, Cisco, Dell).

Uses AI-based profiling to continuously update device fingerprints.

???? Real-World Application:

Improved security policies (Only authorized devices can access the network).

QoS and network optimization based on device type.

Dynamic access control based on OS and manufacturer.

✅ Reference: Huawei HCIE-Datacom Guide – AI-Driven Campus Networks with iMaster NCE