HCSP Presales H19-402_V1.0 Updated Exam

In Huawei CloudFabric VXLAN design, distributed gateway architecture is a key enhancement over traditional centralized gateway models, especially for large-scale data centers.

Option A is correct because distributed gateways (typically deployed on leaf nodes) only maintain local ARP/MAC entries for directly connected hosts. This significantly reduces ARP table pressure compared to centralized gateways, where a single device must learn all entries. This improves scalability and performance , which is critical in multi-tenant environments.

Option C is also correct as Huawei leaf switches can simultaneously act as Layer 2 VXLAN gateways (bridging) and Layer 3 VXLAN gateways (routing) . This enables distributed inter-subnet routing directly at the access layer, reducing latency and improving east-west traffic efficiency.

Option B is incorrect because it describes a limitation of centralized gateways , where traffic must traverse a central node, leading to suboptimal paths. Distributed gateways eliminate this issue.

Option D is also incorrect as it again describes centralized gateway constraints, not distributed ones.

Thus, distributed VXLAN gateways provide better scalability, optimal forwarding paths, and flexible deployment , making A and C correct .

In Huawei VXLAN architecture, different gateway types serve distinct roles in tenant communication. The Layer 2 VXLAN gateway is specifically responsible for providing tenant access to the VXLAN network and enabling intra-subnet communication .

A Layer 2 VXLAN gateway (D) connects traditional Layer 2 networks (such as VLAN-based access networks) to the VXLAN overlay. It allows tenant devices or servers to access the VXLAN fabric while maintaining Layer 2 forwarding within the same subnet (same BD/VNI). This means hosts in the same subnet can communicate directly without requiring Layer 3 routing.

In contrast, Layer 3 VXLAN gateways (B) and centralized VXLAN gateways (C) are used for inter-subnet communication , enabling routing between different VXLAN segments. The default VXLAN gateway (A) typically refers to the default gateway IP configured for hosts, which is implemented via Layer 3 gateway functionality.

Huawei CloudFabric design clearly separates Layer 2 access (tenant onboarding and intra-subnet forwarding) from Layer 3 gateway functions (inter-subnet routing) .

Therefore, the correct answer is D (Layer 2 VXLAN gateway) .

In Huawei CloudFabric design, M-LAG (Multi-Chassis Link Aggregation) is widely used to provide active-active forwarding and high availability at the access and border layers. When border leaf nodes are deployed in an M-LAG pair, they typically connect to upstream PE (Provider Edge) devices in a dual-homing (square topology) manner, ensuring both link-level and device-level redundancy.

However, Huawei design guidelines clearly state that an interconnection link (commonly called a peer-link or bypass link) between M-LAG devices is mandatory. This link is essential for synchronization of forwarding states, MAC address tables, ARP/ND entries, and control plane information between the two devices. It also ensures proper traffic forwarding in failure scenarios, such as when one device loses its uplinks but remains operational.

Without this peer-link, traffic consistency and loop prevention mechanisms cannot function correctly, leading to potential traffic loss or loops. Therefore, even in dual-egress scenarios with PE devices, the bypass/peer link is still required.

Hence, the statement is FALSE.

Huawei M-LAG 2.0 is designed to provide ultra-fast convergence and high availability in modern data center networks. One of its key enhancements over traditional M-LAG implementations is the ability to achieve fast fault detection and rapid switchover , minimizing service interruption.

In the event of a single point of failure (such as link or device failure), M-LAG 2.0 leverages mechanisms like BFD (Bidirectional Forwarding Detection) and optimized peer-link synchronization to quickly detect failures and redirect traffic. The switchover time is typically around 5 milliseconds , ensuring near hitless failover for critical services.

This ultra-fast convergence is particularly important for applications such as AI workloads, financial systems, and real-time services , where even small delays can impact performance.

Compared to traditional technologies (which may take tens or hundreds of milliseconds), Huawei M-LAG 2.0 significantly improves network reliability, service continuity, and user experience .

Therefore, the correct answer is C (5 ms) .