Pass the Huawei HCIE-Datacom H12-891_V1.0 Questions and answers with CertsForce

VXLAN Inter-Subnet Routing with Symmetric IRB

VXLAN supports inter-subnet routing using Integrated Routing and Bridging (IRB). In symmetric IRB, both ingress and egress VTEPs perform Layer 3 forwarding to ensure efficient packet forwarding across subnets.

✅ A. Both the ingress VTEP and egress VTEP forward packets based on the Layer 3 forwarding table.

In symmetric IRB, both ingress and egress VTEPs perform Layer 3 lookup and forwarding.

The ingress routes packets before encapsulating them in VXLAN, and the egress performs another Layer 3 lookup to determine final delivery.

✅ D. When VTEPs forward inter-subnet user communication packets, the VNI carried in the VXLAN header is the L3VNI.

L3VNI (Layer 3 VXLAN Network Identifier) is used for inter-subnet routing between VXLAN segments.

Comprehensive and Detailed Explanation:

The OSPF error output shows:

✔ Hello timer mismatch (1 error) → Hello intervals must match for adjacency formation (A) ✅

✔ No Netmask mismatch errors → Subnet masks are consistent, so option C is incorrect ❌

✔ No Extern option mismatch → No evidence of area type inconsistency (option D) ❌

✔ If area IDs were mismatched, adjacency would not form (option B is correct) ✅

Thus, the correct answers are A and B.

???? Reference: Huawei HCIE Datacom – OSPF Troubleshooting

Virtual Networks in Huawei CloudCampus Solution:

Virtual networks (VNs) are segmented based on services (e.g., IoT, Guest Wi-Fi, Enterprise Wi-Fi).

Each VN has its own routing and forwarding instance (VRF).

Isolation Between Virtual Networks:

By default, different virtual networks are isolated.

If inter-VN communication is required, it must be manually configured using policy-based routing (PBR), inter-VRF routing, or firewall policies.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Solution Guide – Virtual Networks and Segmentation

HCIE-Datacom Training Material – Policy-Based Inter-VN Communication

Huawei SD-WAN establishes secure tunnels between SD-WAN edge devices (CPEs, AR routers, and controllers) using tunneling protocols.

✅ B. GRE over IPsec (Correct Answer)

GRE (Generic Routing Encapsulation) over IPsec is the primary tunneling method used in Huawei SD-WAN.

GRE provides multi-protocol encapsulation, while IPsec ensures encryption and security.

Used for secure communication over public WAN links (e.g., the internet, LTE, MPLS, etc.).

Understanding screen-length Command in Huawei Devices

???? What Does screen-length Do?

Controls how much output is displayed at a time on the Huawei CLI.

By default, command output is paginated (split-screen display).

screen-length 0 temporary disables the split-screen display, allowing continuous output without pauses.

Analysis of Each Option:

❌ A. Performing automatic word wrap → Incorrect

This command does not wrap long text lines, it controls screen pagination.

❌ B. Performing split-screen display → Incorrect

This command disables split-screen display, not enables it.

✅ C. Canceling split-screen display → Correct

This allows continuous command output without " Press Enter to continue " interruptions.

❌ D. Canceling automatic word wrap → Incorrect

Word wrap behavior is not controlled by screen-length.

Real-World Application:

Automated Network Monitoring: Used in Python scripts for uninterrupted CLI output collection.

Log Analysis: Helps in extracting large command outputs for troubleshooting.

✅ Reference: Huawei HCIE-Datacom Guide – CLI Configuration and Automation with Paramiko

In IPsec, a symmetric encryption algorithm (e.g., AES) is used for encrypting data due to its speed. To securely exchange the symmetric key between peers, asymmetric encryption algorithms (like RSA) are used.

This method ensures:

High performance (due to fast symmetric encryption)

Secure key exchange (asymmetric protection)

Exact Extract - Huawei HCIE-Datacom Guide – IPsec Encryption:

“IPsec uses symmetric algorithms to encrypt data for performance and asymmetric algorithms to securely exchange symmetric keys during IKE negotiation.”

When Spanning Tree Protocol (STP) is not enabled on a network, loops can occur in Layer 2 Ethernet networks, leading to various network issues. STP is designed to prevent loops by blocking redundant paths, and its absence can cause broadcast storms, MAC address table instability, and resource exhaustion. Let’s analyze each option in the context of Huawei HCIE Datacom documentation and network behavior:

A. A loop alarm is generated on the LAN switch.

This option is incorrect. Huawei switches, as per HCIE Datacom standards, do not automatically generate a specific " loop alarm " unless configured with loop detection features (e.g., Huawei’s Loop Detection Protocol or similar mechanisms). Without STP or loop detection enabled, the switch may not explicitly generate an alarm for a loop; instead, it will exhibit symptoms like broadcast storms or flapping MAC entries. Therefore, this is not a direct symptom of an STP-less loop. Reference: Huawei HCIE Datacom V3.0 Training Materials, Section 4.2 – Spanning Tree Protocol and Loop Prevention.

B. CPU usage is too high.

This option is correct. When a loop occurs without STP, broadcast packets (and sometimes multicast or unknown unicast packets) circulate endlessly in the network. This leads to excessive processing by switches as they handle these packets, resulting in high CPU usage. Huawei switches, as described in HCIE Datacom documentation, can experience CPU overload due to continuous packet forwarding and processing in a looped environment. Reference: Huawei HCIE Datacom V3.0, Chapter 5 – Switch Performance and Loop Management.

C. MAC entries flap.

This option is correct. In a loop without STP, switches continuously receive frames from multiple ports, causing MAC address tables to update repeatedly as the same MAC address appears on different ports. This " flapping " of MAC entries destabilizes the network and can lead to incorrect frame forwarding. Huawei HCIE Datacom emphasizes MAC address table stability as a critical aspect affected by loops, as outlined in Section 4.3 – Ethernet Switching and Loop Mitigation. Reference: Huawei HCIE Datacom V3.0, Section 4.3.

D. Host receives a large number of broadcast packets.

This option is correct. A loop without STP causes broadcast packets to circulate indefinitely, creating a broadcast storm. Hosts connected to the network will receive an overwhelming number of these packets, potentially leading to performance degradation or even network timeouts. This is a well-documented symptom in Huawei HCIE Datacom training, specifically in discussions about loop prevention mechanisms. Reference: Huawei HCIE Datacom V3.0, Chapter 4 – Layer 2 Loop Prevention.

Thus, the correct symptoms of a loop occurring due to the absence of STP include high CPU usage, flapping MAC entries, and hosts receiving a large number of broadcast packets. Option A is incorrect as it requires specific loop detection configuration, which is not implied in the question.

Comprehensive and Detailed In-Depth Explanation:

1. Free Mobility in Huawei Campus Networks:

Free mobility allows users to move freely within a campus network while retaining their access rights and security policies. It leverages iMaster NCE-Campus as the controller to simplify the deployment and management of user policies.

2. Role of the Administrator:

Administrators are responsible for defining high-level policies and security configurations. Specifically:

Define a Policy Control Matrix:

Administrators create a matrix that specifies how users from different security groups interact.

This matrix outlines access permissions and is a part of the policy planning phase.

Define Security Groups:

Administrators categorize users, devices, or endpoints into security groups based on their roles or functions.

These groups form the basis for applying uniform policies within the network.

3. Role of iMaster NCE-Campus (Controller):

The controller handles the automatic delivery of configured policies and security settings to network devices.

Deliver IP-Security Group Entries:

Once the administrator defines the policies and groups, iMaster NCE-Campus automatically distributes the IP-Security Group Binding entries to the relevant network devices.

This ensures consistent policy enforcement across the campus.

4. Why This Mapping Is Correct:

Administrators define the structure and policies, while the controller (iMaster NCE-Campus) handles the implementation and distribution.

This division of responsibilities optimizes the network management process, reducing human error and ensuring that policies are consistently applied.

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 Protocol Trace function of iMaster NCE-CampusInsight allows O & M teams to analyze the full packet exchange process (e.g., DHCP, authentication, IP acquisition) between clients and the network. In this scenario, it helped pinpoint DHCP address pool exhaustion as the cause.

Exact Extract - Huawei iMaster NCE-CampusInsight Product Documentation:

“The Protocol Trace function visualizes packet-level interaction processes for DHCP, ARP, 802.1X, and others, allowing fast identification of root causes for network access issues.”