H19-402_V1.0 HCSP-Presales – Data Center Network Planning and Design V1.0 Questions and Answers

According to Huawei data center network design guidelines, the selection of an underlay routing protocol depends on the scale and complexity of the network. For small to medium-sized data centers , particularly when the number of ToR (Top of Rack) switches is less than 100 , OSPF (Open Shortest Path First) is the recommended routing protocol.

OSPF is a mature and widely deployed link-state protocol that offers fast convergence, simple configuration, and strong interoperability. It is well-suited for smaller-scale spine-leaf networks where operational simplicity is a priority. Huawei recommends OSPF in such scenarios because it provides sufficient scalability and performance without the added complexity of protocols like BGP.

For larger-scale data centers (typically more than 100 ToR switches), Huawei suggests using IS-IS or BGP to improve scalability and simplify large-scale route management. RIP is not suitable due to its limitations in scalability and convergence speed.

Therefore, for networks with fewer than 100 ToR switches, OSPF is the optimal and recommended choice .

In Huawei CloudFabric architecture, service integration and flexible deployment of security devices such as firewalls are key design principles. Firewalls can be deployed in multiple ways depending on service requirements, traffic patterns, and scalability considerations.

Firewalls can be connected to:

Service leaf nodes : These are dedicated nodes used for service insertion (e.g., firewall, load balancer). Traffic can be steered through these nodes using policy-based routing or service chaining.

Border leaf nodes (combined with service leaf role) : In some designs, border leaf nodes (which connect to external networks such as WAN or Internet) can also integrate service functions, including firewall connectivity. This reduces hardware requirements and simplifies deployment.

Huawei supports both centralized and distributed service deployment models , allowing firewalls to be flexibly inserted into the network fabric. Integration is typically achieved using VXLAN, EVPN, and service chaining technologies , ensuring seamless traffic steering and policy enforcement.

This flexibility enhances:

Network scalability

Security enforcement

Operational simplicity

Therefore, the statement is TRUE .

In Huawei CloudFabric architecture, iMaster NCE-Fabric acts as the central network controller and automation platform that directly integrates with server virtualization platforms such as FusionSphere, VMware vCenter, and OpenStack . This integration enables automated network provisioning, policy enforcement, and dynamic resource orchestration between compute and network layers.

Through northbound APIs, iMaster NCE-Fabric communicates with virtualization platforms to obtain tenant, VM, and network information. It then translates these requirements into fabric configurations, such as VXLAN, EVPN, and underlay routing policies. This tight integration is essential for automated service deployment and end-to-end orchestration , which is a core capability in Huawei’s CloudFabric solution.

On the other hand, iMaster NCE-FabricInsight is focused on intelligent O & M, monitoring, and analytics . It provides telemetry-based visibility, fault detection, and performance optimization, but it does not directly connect to or integrate with virtualization platforms for service provisioning.

Therefore, the correct answer is iMaster NCE-Fabric , as it is the component responsible for connecting to server virtualization systems and enabling automation.

Huawei CloudFabric is designed with an open and extensible ecosystem , enabling seamless integration with multiple platforms and services across modern data center environments. This openness is a key principle in Huawei’s architecture, ensuring interoperability and flexibility for diverse workloads.

Third-party VAS interconnection (A) is supported to allow integration with value-added services such as firewalls, load balancers, and security appliances, enabling service chaining and enhanced network functionality.

Container platform interconnection (B) is critical in cloud-native environments. CloudFabric integrates with platforms like Kubernetes, allowing automated network provisioning for containerized applications through APIs and SDN control.

Cloud platform interconnection (C) includes integration with cloud management platforms such as OpenStack and Huawei ManageOne, enabling unified orchestration of compute, storage, and network resources.

Virtualization platform interconnection (D) supports platforms like VMware and FusionSphere, allowing dynamic VM-based networking and automated service deployment.

Huawei documentation emphasizes that CloudFabric supports all these interconnection scenarios to deliver full-stack, multi-platform integration , making all options correct.

In Huawei data center network design, M-LAG (Multi-Chassis Link Aggregation) is widely used to build loop-free Layer 2 topologies without relying on Spanning Tree Protocol (STP) . This is a key advantage in modern CloudFabric architectures.

Traditional Layer 2 networks depend on STP to prevent loops, but STP introduces drawbacks such as blocked links, slow convergence, and inefficient bandwidth utilization . M-LAG eliminates these issues by allowing two physical switches to operate as a single logical device from the perspective of downstream nodes.

With M-LAG:

All links are active-active , maximizing bandwidth usage

Loop prevention is achieved through protocol mechanisms and peer-link synchronization , not STP

Convergence is much faster compared to STP-based designs

Network design becomes simpler and more predictable

Huawei best practices strongly recommend disabling STP in M-LAG-based data center fabrics , especially when combined with VXLAN EVPN, to achieve high performance, fast convergence, and simplified operations .

Therefore, the statement is TRUE .

The key difference between M-LAG and stacking in Huawei data center design lies in their control plane architecture and fault domains .

Option A is false because M-LAG does NOT have a centralized control plane . Instead, each device in an M-LAG pair maintains its own independent control plane , while synchronizing state information (such as MAC and ARP tables) over the peer-link. This distributed control design improves reliability and avoids a single point of failure.

Option B is correct : M-LAG involves two independent switches , both of which must be managed (though automation tools like iMaster NCE-Fabric simplify this).

Option C is correct : M-LAG provides fault domain isolation . A failure on one device does not impact the control plane of the other, enhancing network resilience.

Option D is correct : In contrast, stacking uses a single control plane , so upgrades can be more complex and potentially disruptive, affecting the entire stack.

Huawei best practices favor M-LAG over stacking in modern data centers due to its distributed control, higher reliability, and better fault isolation .

Therefore, the correct answer is A .

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) .

In Huawei CloudFabric architecture, logical switches are a key abstraction used to simplify network service deployment and management. These logical switches are built on top of VXLAN Layer 2 networks and represent virtualized broadcast domains (similar to VLANs, but more scalable).

Huawei extends the function of these logical switches by integrating distributed Layer 3 gateway capabilities directly into them. This means that each logical switch can provide both Layer 2 connectivity and Layer 3 routing services (commonly referred to as distributed gateways). These gateways are typically implemented on leaf nodes using VXLAN with BGP EVPN as the control plane.

As a result, traffic between subnets can be routed locally at the ingress leaf switch without needing to traverse to a centralized gateway, significantly improving efficiency and reducing latency. Logical ports connected to these logical switches automatically receive gateway services, enabling seamless inter-subnet communication.

This design aligns with Huawei’s intent of decoupling physical and logical networks while providing scalable, agile, and highly efficient data center networking. Therefore, the statement is TRUE.

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 data center design guidelines emphasize end-to-end reliability across all layers of the physical network, including uplinks, devices, interconnections, and server access. All the listed options reflect valid reliability principles.

Option A is correct because ECMP (Equal-Cost Multi-Path) is a fundamental mechanism in spine-leaf architectures, ensuring load balancing and fast convergence when links fail. Option B highlights modular switch reliability , where inter-card connections prevent single-card failures from impacting connectivity.

Option C describes the DAD (Dual-Active Detection) mechanism in M-LAG scenarios. When a peer-link failure occurs, DAD ensures that only one device remains active, preventing split-brain conditions and maintaining network stability.

Option D addresses server-side reliability , where dual-homing with NIC teaming (active-active or active-standby) ensures uninterrupted service in case of link or device failure.

Together, these principles form Huawei’s comprehensive approach to building highly reliable and resilient data center networks.

In Huawei data center network design, particularly in large-scale CloudFabric architectures, Points of Delivery (PoDs) are a fundamental concept used to enable modular scalability, simplified management, and efficient resource pooling. A PoD typically consists of a group of servers, access switches (Leaf), and sometimes aggregation resources that function as a repeatable building block within the data center.

By dividing a data center into multiple PoDs, operators can achieve horizontal scalability , where additional capacity is added by deploying new PoDs without impacting existing services. This aligns with Huawei’s spine-leaf architecture, where each PoD connects to a common spine layer, ensuring consistent performance and low latency.

PoDs also improve fault isolation and operational efficiency , as issues can be contained within a specific module. From a management perspective, this structure simplifies provisioning, monitoring, and automation through platforms like iMaster NCE-Fabric.

Therefore, the statement is TRUE , as PoD-based design is a widely adopted best practice in Huawei data center planning and modern cloud infrastructures.

In Huawei CloudFabric architecture, server leaf nodes and service leaf nodes have distinct roles, even though both can function as NVEs (Network Virtualization Edge devices) in a VXLAN network.

A server leaf node primarily provides access for compute resources , such as physical servers and virtual machines. It acts as a common NVE, handling VXLAN encapsulation/decapsulation for tenant traffic and enabling communication within the overlay network.

However, firewalls and load balancers (LBs) are classified as value-added service (VAS) devices and are typically connected to service leaf nodes , not standard server leaf nodes. Service leaf nodes are specifically designed to handle service insertion, traffic steering, and policy-based forwarding required for these devices.

Although in some simplified deployments roles may be combined, Huawei standard design clearly separates:

Server leaf → compute access

Service leaf → VAS device access (FW, LB, etc.)

Therefore, the statement is FALSE , as server leaf nodes do not typically provide access for firewalls and load balancers in standard CloudFabric architecture.

In Huawei CloudFabric architecture, the underlay network is the physical IP fabric, while the overlay network is a logical network built on top of it using technologies like VXLAN and BGP EVPN .

Option A is false because the overlay network does not require bare optical fibers . It operates independently of the physical medium and can run over any IP-based underlay (Ethernet, optical, etc.). The overlay abstracts the physical infrastructure.

Option B is correct : the underlay network is transparent to endpoints (servers, firewalls, routers). These devices only interact with the overlay and are unaware of the underlying transport.

Option C is correct : the overlay has its own forwarding plane (VXLAN encapsulation) and control plane (BGP EVPN) , enabling scalable and automated network virtualization.

Option D is correct : the overlay is a logical network built over the underlay , providing tenant isolation and flexible service deployment.

Huawei best practices emphasize decoupling overlay from underlay , ensuring flexibility, scalability, and simplified operations.

Therefore, the correct answer is A .

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 CloudFabric intelligent O & M (Operations and Maintenance), multiple southbound data collection protocols are supported to enable comprehensive monitoring, analysis, and fault diagnosis. Commonly supported protocols include Telemetry, SNMP, NetStream, and ERSPAN .

Telemetry is the primary modern mechanism, providing real-time streaming data with high accuracy and low latency. SNMP is used for traditional device monitoring and alarm collection. NetStream (Huawei’s implementation of NetFlow) is used for traffic analysis, while ERSPAN enables remote traffic mirroring for deep packet inspection and troubleshooting.

However, Qx is not a standard or supported southbound protocol in Huawei CloudFabric O & M architecture. It is not referenced in Huawei documentation as a mechanism for data collection or monitoring.

Therefore, option B is correct because it identifies the protocol that is not supported , while all other options are valid and commonly used in Huawei intelligent O & M solutions.