Huawei Updated H19-402_V1.0 Exam Questions and Answers by dana

In Huawei CloudFabric architecture, the underlay network is defined as a pure IP transport (bearer) network whose primary role is to provide Layer 3 reachability between VTEPs (VXLAN Tunnel Endpoints) . It is designed to be simple, stable, and highly reliable , typically composed of spine and leaf switches running routing protocols such as OSPF, IS-IS, or EBGP .

The statement is false because it incorrectly includes LBs (load balancers) and firewalls as part of the underlay network. In Huawei design principles:

Underlay = physical IP forwarding infrastructure (switch fabric only)

Overlay/services = VAS devices (firewalls, load balancers, etc.)

Firewalls and load balancers are considered service devices (VAS) and are usually connected via service leaf nodes or border leaf nodes , operating in the overlay/service layer , not as part of the underlay forwarding plane.

Additionally, the underlay is typically implemented using a spine-leaf architecture , not traditional three-tier (core/aggregation/access) designs.

Therefore, the statement is FALSE .

In Huawei data center networking, especially within Intelligent Lossless Data Center Network design, incast traffic is a well-known challenge in distributed systems such as AI computing clusters and distributed storage architectures .

In an incast scenario , a large number of servers simultaneously send traffic to a single destination (e.g., parameter server in AI training or storage node in distributed storage). This sudden aggregation of traffic can quickly overflow switch buffers , leading to packet loss, increased latency, and throughput degradation .

Huawei identifies incast as a primary cause of network congestion in modern data centers. To mitigate this, CloudFabric solutions implement advanced congestion control technologies such as:

PFC (Priority Flow Control) to prevent packet loss

ECN (Explicit Congestion Notification) for early congestion signaling

AI-driven traffic scheduling and load balancing

These mechanisms help build a lossless Ethernet fabric , which is essential for RDMA-based AI workloads and high-performance storage systems.

Therefore, the statement is TRUE , as incast traffic is indeed prone to causing congestion in such environments.

According to Huawei’s CloudFabric intelligent O & M description, the health model is built as a multi-dimensional evaluation system that assesses the network from five dimensions: device, network, protocol, overlay, and service . This means every option listed in the question is part of the CloudFabric health model. Huawei explains that this model integrates telemetry-assisted data such as configuration data, forwarding entry data, logs, and KPI performance information, allowing the platform to detect faults and risks in real time across these five layers.

In practical Huawei CloudFabric operations, the device layer focuses on node health, hardware state, and resource status; the network layer checks connectivity and path quality; the protocol layer verifies control-plane protocols and convergence behavior; the overlay layer evaluates virtualized forwarding networks such as VXLAN fabrics; and the service layer measures the actual service experience and traffic exchange status. Huawei explicitly presents these five as the full health-evaluation scope of CloudFabric intelligent O & M, so the correct response is all five options

In Huawei data center network design, VXLAN overlay deployment models are categorized based on where VTEPs (VXLAN Tunnel End Points) are located. These include host-based overlay, network-based overlay, and hybrid overlay.

In a host overlay , VTEPs are implemented only on vSwitches (such as those within hypervisors), and physical switches only provide IP transport (underlay). In a network overlay , VTEPs are deployed only on physical switches (typically leaf switches), and servers are unaware of VXLAN encapsulation.

The hybrid overlay model combines both approaches. In this design, VTEPs can exist on both vSwitches (inside virtualized hosts) and physical switches (such as leaf devices). This allows greater flexibility, supporting mixed environments where some workloads use hypervisor-based encapsulation while others rely on hardware VTEPs for higher performance or integration with bare-metal servers.

Huawei CloudFabric supports hybrid overlay to enable smooth evolution from traditional to fully virtualized environments. Therefore, the correct answer is Hybrid overlay (C) .