H12-891_V1.0 Sample Questions Answers

MPLS Positioning in the TCP/IP Model

MPLS (Multiprotocol Label Switching) operates between the Data Link Layer (Layer 2) and the Network Layer (Layer 3).

✅ MPLS is protocol-independent and supports various network layer protocols (IPv4, IPv6, VPN, etc.) by using labels instead of traditional IP routing.

✅ How MPLS Works:

MPLS assigns labels to packets, allowing fast forwarding based on the label rather than a routing table lookup.

Supports Layer 3 VPNs (L3VPNs), Layer 2 VPNs (L2VPNs), and MPLS Traffic Engineering (MPLS-TE).

✅ Why MPLS is Between Layer 2 and Layer 3?

MPLS adds a label between the Layer 2 (Ethernet, PPP) and Layer 3 (IP) headers, effectively creating a separate forwarding mechanism.

Label Switching Routers (LSRs) forward packets based on labels instead of IP addresses, reducing processing time.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – MPLS Architecture and Label Switching

HCIE-Datacom Study Material – MPLS Positioning and Functionality in TCP/IP

Static information collection and analysis refers to gathering non-changing (static) parameters of the network devices. These parameters are mostly configuration-related and do not fluctuate dynamically.

Explanation of Correct Options:

✅ A. Device types

Includes information about the hardware platform, model, and series of the device.

Example: Huawei NE40E, CE12800, or AR routers.

✅ C. License

Licenses define feature capabilities, such as MPLS, BGP, or security functions.

Licenses are static parameters because they do not change unless manually updated.

Incorrect Options:

❌ B. Interface types

Interface types (GigabitEthernet, FastEthernet, Serial, etc.) can change depending on hardware or software configurations.

They are not static because interfaces can be added or removed dynamically.

❌ D. Packet loss rate

Packet loss rate is a dynamic parameter, as it varies depending on network conditions, congestion, or faults.

It is used in performance monitoring rather than static data collection.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Network Management Best Practices – Static & Dynamic Data Collection

HCIE-Datacom Guide – Network Monitoring and Analysis

Huawei NCE-Campus Network Health Check Manual

Comprehensive and Detailed Explanation:

✔ gRPC supports four types of RPCs:

Unary RPC → Client sends one request, server responds once.

Server streaming RPC → Server sends multiple responses.

Client streaming RPC → Client sends multiple requests.

Bidirectional streaming RPC → Both sides exchange multiple messages.

✔ Why B and C Are Incorrect:❌ (B) Incorrect → The method rpc dataPublish(stream serviceArgs) returns(stream serviceArgs) {} violates gRPC syntax.❌ (C) Incorrect → rpc stream LotsOfGreetings(HelloRequest) returns (HelloResponse) {} contains incorrect stream positioning.

???? Reference: Huawei HCIE Datacom – gRPC API and Streaming Mechanisms

Comprehensive and Detailed Explanation:

✔ Huawei OPS (Open Programmability System) is a YANG-based network management system that uses RESTful APIs for configuring and managing devices.

✔ /ifm/interfaces/interface is the RESTful URI (Uniform Resource Identifier) that:

Represents an interface object in the network device.

Allows querying, configuring, and modifying network interfaces via API requests.

Since the statement is correct, the answer is TRUE.

???? Reference: Huawei HCIE Datacom – OPS API and Managed Objects

Understanding Performance Measurement in Huawei CloudWAN

Huawei CloudWAN enables intelligent traffic management, real-time network monitoring, and automated operations.

???? Traditional Performance Monitoring Methods

TWAMP (Two-Way Active Measurement Protocol) → Measures latency and jitter by injecting test traffic.

Telemetry → Provides real-time network visibility, but does not measure actual service traffic performance.

BGP FlowSpec → Used for DDoS mitigation, not performance measurement.

???? iFIT (In-situ Flow Information Telemetry)✅ iFIT is a next-generation performance monitoring technology that measures:

Real service traffic performance (latency, jitter, packet loss) in real time.

Packet forwarding behavior at each hop without injecting synthetic traffic.

Path delay and service degradation detection.

Why is Answer D Correct?

✅ iFIT provides real-time network performance monitoring based on actual service traffic.✅ Unlike TWAMP, iFIT does not require probe packets, reducing overhead.

Real-World Application:

5G Transport Networks: Ensures low-latency paths for ultra-reliable services.

CloudWAN Optimization: Detects network congestion without affecting user traffic.

✅ Reference: Huawei HCIE-Datacom Guide – iFIT and Intelligent Performance Monitoring

Understanding SR-MPLS Label Calculation

SR-MPLS uses Segment Routing Global Block (SRGB) and Prefix SIDs to assign labels dynamically. The MPLS label for a node’s loopback interface is calculated as follows:

MPLS Label=SRGB Base+Prefix SID Index

Where:

SRGB Base = 20000 (as given in the figure)

Prefix SID Index = 30 (configured for R3’s Loopback1)

Label Calculation:

20000+30=20030

Thus, the MPLS label corresponding to the loopback1 interface of R3 is 20030.

Why the Answer is 20030?

✔ The SRGB defines the base label range.✔ Each router is assigned a unique Prefix SID index.✔ The label is dynamically computed by adding the Prefix SID Index to the SRGB Base.

Why Other Numbers Are Incorrect?

❌ Any value outside the range 20000-21000

Would be incorrect because it must be within R3’s SRGB range.

❌ Using the Prefix SID Index directly (30)

Incorrect because MPLS labels are not assigned directly using Prefix SIDs; they are computed using the SRGB.

???? Reference: Huawei HCIE Datacom – SR-MPLS Label Calculation and SRGB

Comprehensive and Detailed Explanation:

IP Source Guard (IPSG) is a Layer 3 security feature used to protect against IP address spoofing by filtering packets based on bound IP-MAC mappings.

Correct Statements:✔ IPSG is a Layer 3 filtering mechanism that checks if the source IP address of a packet matches the learned or configured bindings (Option B).✔ IPSG prevents unauthorized IP address changes by enforcing binding rules (Option C).✔ IPSG defends against IP spoofing attacks by dropping packets from unauthorized sources (Option D).

Incorrect Statement:❌ Option A is incorrect because IPSG does not send alarms to an NMS when an invalid packet is detected. Instead, it drops the packet.

Thus, the correct answer is A.

???? Reference: Huawei HCIE Datacom Security Guide - IP Source Guard (IPSG)

Understanding Jinja2 Templates in Huawei SSP Packages

???? What is Jinja2?

Jinja2 is a templating engine used in Huawei SSP (Smart Script Package) automation.

It allows dynamic configuration generation based on variables and logic.

???? Jinja2 Syntax Basics:✅ {% ... %} → Used for control structures like loops and conditions.✅ {{ ... }} → Used for variable placeholders.

Example of a Jinja2 Template Using {% ... %} for a Loop:

jinja2

CopyEdit

{% for interface in interfaces %}

interface {{ interface.name }}

description {{ interface.description }}

{% endfor %}

???? This template dynamically generates interface configurations based on a list of interfaces.

Why is the Answer TRUE?

✅ {% ... %} is used for control structures in Jinja2 templates (e.g., loops, if-else statements).✅ Jinja2 templates are widely used in SSP for Huawei network automation.

Real-World Application:

Automated Network Configuration: Uses Jinja2 in Huawei SSP automation scripts.

Data Center & SDN Automation: Dynamically generates VXLAN, BGP, and OSPF configurations.

✅ Reference: Huawei HCIE-Datacom Guide – Jinja2 Templates in SSP Packages

Understanding Northbound APIs in Huawei iMaster NCE-WAN

???? What is a Northbound API?

Northbound APIs allow external applications (e.g., SDN controllers, orchestration tools) to communicate with Huawei iMaster NCE-WAN.

Used for automation, monitoring, and network configuration.

Analysis of Each API Type:

✅ A. NETCONF (Network Configuration Protocol)

Correct: NETCONF is an IETF-standardized protocol for network configuration management.

Huawei iMaster NCE-WAN supports NETCONF for dynamic configuration of SD-WAN devices.

✅ B. RESTful API (Representational State Transfer API)

Correct: RESTful APIs provide HTTP-based programmatic access to SD-WAN functions.

Used for cloud-native SD-WAN automation and integration.

❌ C. CLI (Command Line Interface) (Incorrect Choice)

CLI is not a northbound API; it is a manual command interface used directly on devices.

❌ D. SNMP (Simple Network Management Protocol) (Incorrect Choice)

SNMP is used for network monitoring, not for northbound API communications.

Real-World Application:

Cloud-based SD-WAN Automation: Uses RESTful API for seamless integration with third-party cloud orchestration tools.

Zero-Touch Provisioning (ZTP): Uses NETCONF API to push configurations to branch SD-WAN routers.

✅ Reference: Huawei HCIE-Datacom Guide – SD-WAN API Integration and Automation

Comprehensive and Detailed Explanation:

✔ Correct Interpretations from the Output:✅ (A) The subscription name is "Sub1" (Confirmed from output).✅ (C) The subscription is static (PASSIVE state indicates this).✅ (D) The sample interval is 1000ms (1 second).

❌ (B) Incorrect:

The IP address "192.168.56.1" belongs to the destination server, not the local device.

???? Reference: Huawei HCIE Datacom – Telemetry Subscription and Monitoring

Understanding Huawei SD-WAN Tunneling Technologies

Huawei SD-WAN uses secure tunneling to connect branches, data centers, and cloud services.

???? Tunneling Technologies in SD-WAN:✅ IPsec (Answer B) → Provides secure encrypted tunnels over public or private networks.✅ GRE over IPsec (Answer D) → Encapsulates traffic inside GRE, then encrypts with IPsec, enabling support for multicast and non-IP traffic.

❌ A. WLAN (Incorrect Choice) → WLAN is a wireless technology, not a tunneling protocol.❌ C. MPLS (Incorrect Choice) → MPLS is a core network transport technology but is not used to establish SD-WAN data channels directly.

Why are Answers B and D Correct?

✅ Huawei SD-WAN primarily uses IPsec for data encryption.✅ GRE over IPsec is used when supporting multicast or dynamic routing protocols over tunnels.

✅ Reference: Huawei HCIE-Datacom Guide – SD-WAN Tunneling Mechanisms

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

Correct Matching of Authentication Methods:

1️ 802.1X authentication → PC (GE0/0/2 on SW3)2️ MAC address authentication → IP Phone (GE0/0/3 on SW3)3️⃣ Portal authentication → Wireless Clients (Connected via SW2/AP)

Understanding Network Admission Control (NAC) Authentication Methods

???? Network Admission Control (NAC) enforces security policies before allowing devices onto the network.???? Different types of devices require different authentication methods based on capabilities and security requirements.

Analysis of Each Authentication Type:

✅ 1️⃣ 802.1X Authentication (Used for PC on GE0/0/2 of SW3)

Best for devices that support user authentication (e.g., PCs, Laptops).

Requires supplicant software (e.g., Windows or macOS built-in 802.1X client).

Provides strong security using EAP (Extensible Authentication Protocol) over RADIUS.

✅ 2️⃣ MAC Address Authentication (Used for IP Phone on GE0/0/3 of SW3)

Best for devices that do not support username/password authentication (e.g., IP Phones, IoT devices).

Uses MAC addresses as identity credentials.

Suitable for VoIP networks, industrial IoT, and surveillance cameras.

✅ 3️⃣ Portal Authentication (Used for Wireless Clients on SW2/AP)

Best for guests or mobile users accessing Wi-Fi networks.

Redirects users to a web-based login page before granting access.

Used in public hotspots, campus Wi-Fi, and enterprise guest networks.

Why These Assignments Are Correct?

1️⃣ 802.1X for PC:

PCs support 802.1X authentication via supplicants (EAP-MD5, PEAP, etc.).

Ensures high security by verifying user credentials.

2️⃣ MAC Address Authentication for IP Phone:

IP Phones lack a username/password interface, so authentication is done via MAC addresses.

Simplifies authentication while maintaining security.

3️⃣ Portal Authentication for Wireless Clients:

Wireless users do not use 802.1X authentication directly; instead, they are redirected to a web login page.

Common in enterprise guest Wi-Fi and public hotspots.

Real-World Application:

Enterprise NAC Deployment: Ensures only authorized users and devices access the corporate network.

Campus & Hotel Wi-Fi Security: Uses Portal Authentication for guests, 802.1X for employees, and MAC-based for VoIP.

✅ Reference: Huawei HCIE-Datacom Guide – NAC Authentication Methods & Best Practices

Understanding VXLAN (Virtual eXtensible LAN) Technology

VXLAN is a Layer 2 over Layer 3 encapsulation protocol designed to extend Layer 2 domains across routed networks using MAC-in-UDP encapsulation.

???? Key VXLAN Components:

VTEP (VXLAN Tunnel Endpoints): These encapsulate and decapsulate VXLAN packets.

Underlay Network: The routed IP network that forwards VXLAN packets (does not require VXLAN awareness).

Overlay Network: The logical Layer 2 segments tunneled over VXLAN.

Analysis of the Answer Choices:

✅ A. VXLAN uses MAC-in-UDP encapsulation to encapsulate Ethernet packets into UDP packets and thereby extend Layer 2 networks.

Correct: VXLAN uses MAC-in-UDP encapsulation, meaning that the original Ethernet frame is placed inside a UDP packet, allowing Layer 2 networks to extend over IP-based networks.

❌ B. When VXLAN is deployed, in addition to devices at both ends of a VXLAN tunnel, intermediate forwarding devices are also required to support VXLAN. Otherwise, VXLAN packets cannot be forwarded.

Incorrect: VXLAN packets are forwarded as regular UDP traffic in the underlay network.

Intermediate routers or switches DO NOT need to support VXLAN, as they only forward UDP packets based on the outer IP headers.

Only VTEP devices must support VXLAN because they handle encapsulation/decapsulation.

✅ C. VXLAN packets are forwarded through routes on the underlay network, and the MAC address of the terminal in the inner data frame is not considered during underlay forwarding.

Correct: The underlay network routes VXLAN packets using outer IP headers (VTEP IP addresses), not the inner MAC address.

✅ D. VXLAN can be deployed on campus networks to implement Layer 2 and Layer 3 communication.

Correct: VXLAN is commonly used in campus networks to provide both Layer 2 bridging and Layer 3 routing across different locations.

Real-World Application:

Data Center Networks: VXLAN is widely used for multi-tenant network segmentation in cloud environments.

Enterprise Campus Networks: Enables seamless Layer 2 and Layer 3 connectivity across different buildings or locations.

✅ Reference: Huawei HCIE-Datacom Guide – VXLAN Deployment and Forwarding Principles

Comprehensive and Detailed Explanation:

✔ SR-MPLS Policy candidate paths are used for flexible path selection and load balancing in Segment Routing (SR-MPLS) networks.

✔ Correct Statements:✅ (A) Each candidate path can have multiple segment lists, each with its own weight for load balancing.✅ (B) Load balancing is supported both between candidate paths and within segment lists.✅ (C) An SR-MPLS Policy can contain multiple candidate paths, each with a preference value.✅ (D) The candidate path with the highest preference is selected as the primary path.

???? Reference: Huawei HCIE Datacom – SR-MPLS Policy Path Selection

Understanding User Authentication Points in a Network

Authentication points can be deployed at different network layers based on security and scalability needs:

✅ Access Layer Authentication:

Ensures high security & granular control (user-level authentication).

Preferred in high-security enterprise networks.

✅ Aggregation or Core Layer Authentication:

Reduces authentication overhead but provides less granular control.

Suitable for large-scale networks where authentication load needs to be balanced.

Analysis of the Answer Choices:

✅ A. Deploying user authentication points at the access layer achieves granular permission management and high network security.

Correct: Provides fine-grained control per user and prevents unauthorized access.

✅ B. Moving user authentication points from the access layer to the aggregation or core layer greatly reduces the number of user authentication points, thereby effectively mitigating the pressure on the AAA server.

Correct: Fewer authentication points mean less load on the AAA server.

✅ C. Deploying user authentication points at the access layer has both advantages and disadvantages when compared to doing so at the aggregation or core layer. Policy association can be applied if user authentication points are deployed at the access layer.

Correct: Policy-based authentication is best applied at the access layer for granular control.

❌ D. When user authentication points are moved from the access layer to the aggregation layer, MAC address authentication for users may fail.

Incorrect: MAC authentication works at both layers, but policy adjustments may be needed.

✅ Reference: Huawei HCIE-Datacom Guide – User Authentication Strategies in Enterprise Networks

Huawei Open Programmability System (OPS) and Scripting Support

Huawei OPS (Open Programmability System) enables network automation using script-based programming for device management and configuration.

✅ Python is the primary language integrated into Huawei OPS.

Python scripts can automate device configurations, monitoring, and troubleshooting.

OPS supports Python libraries for interacting with network APIs and CLI commands.

Used for Huawei CloudCampus, SDN, and Datacom devices.

Understanding SR-MPLS TE (Segment Routing MPLS Traffic Engineering)

???? What is SR-MPLS TE?

Segment Routing (SR) replaces traditional MPLS LDP/RSVP-TE signaling.

Uses SR-TE policies to define network paths without requiring per-flow state on intermediate routers.

???? How is the SR-MPLS TE Path Calculated?✅ By the SDN Controller (Centralized Path Computation)

The controller (e.g., Huawei iMaster NCE) calculates the optimal SR path based on:

Bandwidth requirements

Latency constraints

Traffic policies

The controller then delivers the SR policy to the ingress router.

✅ By the Ingress Router (Distributed Path Computation)

The ingress router computes the SR path dynamically based on local constraints.

This method is useful when no centralized controller is available.

Why is the Answer TRUE?

✅ Both centralized (controller-based) and distributed (ingress router-based) path computation are supported in SR-MPLS TE.

Real-World Application:

5G and Cloud WANs: Centralized path optimization reduces congestion dynamically.

Enterprise Networks: Local path computation ensures fast rerouting in case of failures.

✅ Reference: Huawei HCIE-Datacom Guide – SR-MPLS TE and Path Computation Methods

Comprehensive and Detailed Explanation:

✔ Fit APs require additional configurations before going online, such as:

AP authentication and onboarding through DHCP Option 148 or manual registration.

Firmware upgrade and provisioning from iMaster NCE-Campus.

Policy enforcement and VLAN assignment.

Since additional steps are required, Fit APs do not go online immediately, making the statement FALSE.

???? Reference: Huawei HCIE Datacom – AP Registration and Authentication

Comprehensive and Detailed Explanation:

The IS-IS metric (cost) determines the shortest path selection.

The isis cost command is used to manually set the cost of an IS-IS interface.

Command Breakdown:

✔ isis cost <value> – Adjusts the cost of an interface in the IS-IS routing protocol.✔ Lower cost means higher priority in route selection.

Why Are Other Options Incorrect?

❌ isis circuit-type – Sets the circuit type (L1, L2, L1/L2) but does not change cost.❌ isis timer hello – Adjusts hello interval timing, not path cost.❌ isis circuit-level – Defines interface level (L1, L2) but does not impact cost.

Thus, the correct answer is C.

???? Reference: Huawei HCIE Datacom – IS-IS Path Cost Adjustment

Understanding Telemetry Encoding Formats

???? What is Telemetry?

Telemetry is a real-time network monitoring method that provides high-frequency data collection.

Used in AI-driven networks for predictive analytics and automation.

???? Common Telemetry Encoding Formats:

✅ GPB (Google Protocol Buffers)

Highly efficient binary format that reduces message size and CPU overhead.

Commonly used for high-speed, real-time analytics.

✅ JSON (JavaScript Object Notation)

Human-readable format, widely used in RESTful APIs.

Less efficient than GPB in high-speed telemetry but easier to debug.

???? Why is the Answer FALSE?❌ GPB is not mandatory; JSON can also be used in telemetry.✅ Huawei supports both GPB and JSON telemetry encoding formats.

Real-World Application:

Cloud Networking: Uses GPB for fast data collection and JSON for API-based telemetry visualization.

AI-Driven Networks: High-speed AI analytics leverage GPB encoding for efficiency.

✅ Reference: Huawei HCIE-Datacom Guide – Telemetry Encoding Formats and Data Collection

Comparison Between Paramiko (SSH) and Telnetlib (Telnet)

✅ Paramiko (SSH) is more secure than Telnetlib (Telnet).

SSH (Secure Shell) encrypts login credentials and session data using encryption protocols like AES and RSA.

Telnet transmits data in plaintext, making it vulnerable to eavesdropping and man-in-the-middle attacks.

✅ Why is Telnet Insecure?

No encryption → Credentials (username/password) are sent in plaintext.

Easily intercepted by attackers using packet sniffers (e.g., Wireshark).

Correct Method for Secure Remote Login in Python:

Use Paramiko for SSH-based secure automation.

Example of logging in with Paramiko (SSH) in Python:

import paramiko

ssh = paramiko.SSHClient()

ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

ssh.connect("192.168.1.1", username="admin", password="password")

stdin, stdout, stderr = ssh.exec_command("display version")

print(stdout.read().decode())

ssh.close()

Reference from Huawei HCIE-Datacom Documentation:

Huawei Security Best Practices – Avoiding Telnet and Using SSH for Secure Access

HCIE-Datacom Training Material – Network Automation with Python (Paramiko & Telnetlib)

Understanding VXLAN and NVE Interfaces

VXLAN (Virtual Extensible LAN) allows for Layer 2 network extension over Layer 3 infrastructure.

???? Key VXLAN Components:

NVE (Network Virtualization Edge) Interface → VXLAN tunnels are created using one or more NVE interfaces.

BD (Bridge Domain) → Logical grouping of VXLAN traffic.

VNI (VXLAN Network Identifier) → 24-bit unique ID for traffic segmentation.

???? Analysis of Each Option:

✅ A. One NVE interface can be used for multiple VXLAN tunnels if ingress replication is used.

Correct: VXLAN tunnels can be dynamically learned using BGP EVPN, meaning multiple tunnels can use the same NVE interface.

✅ B. An NVE interface can be associated with multiple VNIs, allowing multiple BDs on one NVE.

Correct: Each NVE interface can carry multiple VNIs, reducing the need for separate interfaces.

❌ C. One NVE interface must be created per VXLAN tunnel.

Incorrect: Multiple VXLAN tunnels can share a single NVE interface.

❌ D. One NVE must be created for each BD.

Incorrect: One NVE can support multiple BDs.

???? Real-World Application:

Cloud Data Centers: VXLAN enables multi-tenant network segmentation.

Campus Networks: Simplifies Layer 2/Layer 3 connectivity across sites.

✅ Reference: Huawei HCIE-Datacom Guide – VXLAN and NVE Configuration

Understanding BGP Link State (BGP-LS)

???? What is BGP-LS?

BGP-LS (BGP Link-State) is an extension of BGP that allows routers to exchange network topology information via Link-State NLRI.

Helps SDN controllers and path computation elements (PCEs) make intelligent routing decisions.

???? What Does BGP-LS Advertise?✅ Node Information – Router IDs, Loopbacks✅ Link Information – Bandwidth, Delay, Cost✅ Prefix Information – Network Subnets✅ Topology Information – Full network graph

Why is the Answer TRUE?

✅ BGP-LS introduces a new NLRI format for advertising link-state information.✅ NLRI (Network Layer Reachability Information) is used to distribute topology data to SDN controllers.✅ It improves path optimization by enabling centralized traffic engineering decisions.

Real-World Application:

SDN-Based Traffic Engineering: Used in Segment Routing (SR) networks for centralized path selection.

MPLS TE (Traffic Engineering): Optimizes network paths dynamically based on real-time link-state data.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Link-State (BGP-LS) Fundamentals

In BGP/MPLS IP VPN, when OSPF is used as the PE-CE routing protocol, Domain IDs are used to determine whether the OSPF routes imported into the VPN instance belong to the same OSPF domain.

How Domain ID Works in OSPF and MPLS VPN:

Same Domain ID (OSPF Intra-domain routes)

If the PE router's Domain ID matches the OSPF Domain ID, routes are treated as intra-area routes.

The routes retain OSPF attributes when redistributed into the VPN.

Different Domain ID (OSPF Inter-domain routes)

If the Domain ID does not match, routes are treated as external routes (Type 3 or Type 5 LSAs).

The PE router redistributes these routes as OSPF external routes.

Example Huawei Configuration for Domain ID in OSPF VPN:

ospf 1 vpn-instance VPN1

domain-id 1.1.1.1

This ensures consistent OSPF route types when exchanging routes between PE and CE.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – OSPF Domain ID in PE-CE Routing

HCIE-Datacom Study Material – OSPF & MPLS VPN Route Redistribution

Challenges of Static VXLAN Tunnel Configuration

A static VXLAN tunnel requires manual VTEP-to-VTEP configuration, making it complex to maintain.

✅ A. Heavy configuration workload in a distributed gateway scenario

Static VXLAN requires manual configuration of VTEP mappings, making it difficult to scale and adjust when adding new VTEPs.

✅ B. Remote MAC addresses are learned through data flooding

Unlike BGP EVPN-based VXLAN, which advertises MAC/IP bindings through BGP, static VXLAN relies on flooding for MAC learning, causing excessive traffic.

✅ D. N(N-1)/2 tunnels are required for full mesh connectivity

If N devices need to communicate, each must be manually configured with N(N-1)/2 VXLAN tunnels, leading to high administrative overhead.

Incorrect Statement Explanation:

❌ C. Static VXLAN tunnels use protocols on the control plane, consuming device resources.

Wrong! Static VXLAN does not use a control plane protocol like BGP EVPN.

Instead, it relies entirely on static mappings, reducing control plane usage.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN Configuration Guide – Static vs. Dynamic VXLAN Tunnel Establishment

HCIE-Datacom Training Material – Manual Configuration Challenges in Static VXLAN

Comprehensive and Detailed Explanation:

R2 is an Area Border Router (ABR), meaning it connects multiple OSPF areas (Area 0 and Area 1).

ABRs generate Router-LSAs for each area they belong to.

Since R2 is part of both Area 0 and Area 1, it must generate Router-LSAs (Type 1) for both areas.

R2 does not forward Router-LSAs between areas; instead, it generates Summary LSAs (Type 3) to exchange routing information between areas.

Thus, the correct answer is D.

???? Reference: Huawei HCIE Datacom – OSPF LSA Types and ABR Behavior

Comprehensive and Detailed Explanation:

✔ The Best Protection Against MITM and Spoofing Attacks:✅ (D) Associating DHCP Snooping with IPSG (IP Source Guard) and DAI (Dynamic ARP Inspection) provides complete protection by:

Blocking rogue DHCP servers.

Preventing MAC/IP spoofing.

Ensuring only valid clients access the network.

✔ Why Not Other Options?❌ (A) Configuring trusted/untrusted interfaces only helps block rogue DHCP servers, but does not prevent spoofing.❌ (B) Limiting MAC address learning prevents MAC flooding, but does not stop MITM attacks.❌ (C) Checking the CHADDR field in DHCP Snooping helps detect spoofed requests, but does not block all MITM scenarios.

???? Reference: Huawei HCIE Datacom – Security Mechanisms for Intranet Protection

Comprehensive and Detailed Explanation:

✔ Inter-VN communication allows users in different VNs (R&D and Marketing) to communicate.

✔ Correct Steps:✅ (B) Deploy a Policy Control Matrix → Defines rules for inter-VN communication between security groups.✅ (C) Configure Inter-VN Communication → Enables routing between VNs through the border gateway or firewall.

✔ Why Not Other Options?❌ (A) Deploy Network Service Resources → This is for internal VN service deployment, not inter-VN communication.❌ (D) Deploy an External Network → This is for Internet or WAN access, not internal VN-to-VN communication.

???? Reference: Huawei HCIE Datacom – Virtual Network Intercommunication

Comprehensive and Detailed Explanation:

✔ Huawei OPS (Open Programmability System) follows RESTful API principles, using HTTP methods for device management.

✔ HTTP Methods Used in OPS:✅ GET → Retrieves data from the device.✅ POST → Creates new data/configurations.✅ PUT → Replaces entire configuration objects.✅ PATCH → Updates specific fields of a configuration object. ✅ (Correct Answer)

Since PATCH is used for modifying specific values in managed objects, the correct answer is D.

???? Reference: Huawei HCIE Datacom – RESTful API Operations in Huawei OPS

Understanding Network Monitoring Data Categories

???? Network devices operate across three functional planes:

✅ A. Management Plane:

Handles device configuration, authentication, and monitoring.

Example: SNMP, SSH, NETCONF logs.

✅ B. Data Plane (Forwarding Plane):

Handles packet forwarding and switching.

Example: Interface statistics, traffic rates, dropped packets.

✅ C. Control Plane:

Handles routing, signaling, and protocol operations.

Example: BGP, OSPF, and MPLS signaling messages.

❌ D. Monitoring Plane (Incorrect Choice):

There is no "monitoring plane" in network architecture.

Monitoring tools collect data from management, control, and data planes, but do not form a separate plane.

Why is the Answer D (Monitoring-plane data)?

❌ Monitoring-plane does not exist as a separate category in network architecture.✅ O&M tools collect data from management, control, and data planes, but do not define a separate "monitoring plane".

Real-World Application:

Huawei iMaster NCE-Campus & iMaster NCE-WAN collect real-time network statistics and alarms.

Network Performance Monitoring (NPM) tools analyze control-plane events to detect failures.

✅ Reference: Huawei HCIE-Datacom Guide – Network Planes and Performance Monitoring

Understanding "Two-City Three-Center" Networking

???? What is "Two-City Three-Center" Networking?

A high-availability disaster recovery (DR) solution used by financial institutions, government, and enterprise networks.

"Two cities" → Indicates that data centers are deployed in two different locations for redundancy.

"Three centers" → Includes two active data centers + one remote disaster recovery center.

Bearer WAN Layers in "Two-City Three-Center" Networks

✅ A. Core Layer

Provides high-speed backbone connectivity between different data centers.

Uses high-capacity routers and optical links for long-distance communication.

✅ B. Aggregation Layer

Connects access sites to the core network.

Aggregates traffic from branch offices, remote sites, and smaller data centers.

✅ D. Access Layer

Connects end-users, remote branches, and applications to the WAN.

Uses CE (Customer Edge) routers and firewalls to ensure secure access.

❌ C. Control Layer (Incorrect Choice)

The control plane exists in networking, but it is not a physical bearer WAN layer.

The control layer is a logical function, not a network topology layer.

Real-World Application:

Banking Networks: Ensures that core banking applications remain available even in case of a disaster.

Government Data Centers: Enables cross-city data replication for public services.

✅ Reference: Huawei HCIE-Datacom Guide – "Two-City Three-Center" Network Design

From the IS-IS error output, the key error is:

Mismatched Area Addr(L1): 13

This clearly indicates that the area addresses are different, which prevents the Level-1 adjacency from forming.

Why is Option D Correct?

IS-IS Level-1 routers must have the same area ID to form an adjacency.

Since the log shows a mismatched area address, the adjacency fails at Level-1.

If R3 and R4 were Level-2 routers, they could form an adjacency even with different area IDs.

Why Are the Other Options Incorrect?

❌ Option A: No authentication failure is reported.❌ Option B: No "Mismatched Level" errors appear, so their levels are compatible.❌ Option C: No "Bad Circuit Type" errors indicate mismatched circuit types.

Thus, the correct answer is D.

???? Reference: Huawei HCIE Datacom – IS-IS Neighbor Troubleshooting

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 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

Understanding OSPF Multi-Area Routing

???? OSPF (Open Shortest Path First) is a link-state routing protocol that uses a hierarchical area design for scalability.???? OSPF Areas in the Diagram:

Area 0 (Backbone Area): Contains R4 (Loopback 10.0.4.4/32).

Area 1: Contains R1 (Loopback 10.0.1.1/32) and R2 (Loopback 10.0.2.2/32).

Area 2: Contains R3 (Loopback 10.0.3.3/32) and R5 (Loopback 10.0.5.5/32).

R1 and R2 connect Area 1 to Area 0.

R1 and R3 connect Area 1 to Area 2.

How OSPF Advertises Routes Across Areas

✅ Intra-area communication (within the same area) is always possible.✅ Inter-area communication is possible if the ABR (Area Border Router) correctly advertises routes.✅ OSPF does NOT automatically advertise routes from one non-backbone area (e.g., Area 2) to another (e.g., Area 0) unless explicitly allowed.

Analysis of the Answer Choices:

❌ A. 10.0.3.3 and 10.0.5.5 (Incorrect)

Both R3 (10.0.3.3) and R5 (10.0.5.5) are in Area 2.

R3 and R5 can communicate directly, but OSPF rules require an Area Border Router (ABR) to share routing information between areas.

Since no information is provided about inter-area route redistribution, we cannot confirm that R3 and R5 can reach each other.

❌ B. 10.0.2.2 and 10.0.5.5 (Incorrect)

R2 (10.0.2.2) is in Area 1, and R5 (10.0.5.5) is in Area 2.

R2 does NOT have direct OSPF reachability into Area 2.

✅ C. 10.0.2.2 and 10.0.3.3 (Correct)

R2 (10.0.2.2) is in Area 1, and R3 (10.0.3.3) is in Area 2.

R1 connects both Area 1 and Area 2, meaning R2 and R3 can communicate via R1.

R1 is the ABR (Area Border Router) between Area 1 and Area 2, so it will advertise routes from R3 to R2 and vice versa.

❌ D. 10.0.4.4 and 10.0.2.2 (Incorrect)

R4 (10.0.4.4) is in Area 0 (Backbone), and R2 (10.0.2.2) is in Area 1.

R2 does NOT connect directly to Area 0, so R2 does not learn routes from Area 0 unless R1 explicitly redistributes them.

No explicit information about route redistribution is provided.

Final Answer: C (10.0.2.2 and 10.0.3.3)

✅ Reference: Huawei HCIE-Datacom Guide – OSPF Multi-Area Routing & ABR Role

Real-World Application:

Enterprise WAN Networks: Multi-area OSPF is used to scale large enterprise networks while maintaining fast convergence.

Service Provider Networks: ABRs control route distribution, preventing unnecessary flooding of routing updates across areas.

Huawei iMaster NCE-Campus provides open APIs for seamless integration with third-party applications and services. Each API serves a specific purpose in managing network security, operations, analytics, and user interactions.

1. Authentication and authorization → Third-party authentication API

This API is used to integrate third-party authentication systems, such as:

LDAP (Lightweight Directory Access Protocol)

RADIUS (Remote Authentication Dial-In User Service)

OAuth/OpenID authentication

It ensures secure user identity verification, access control, and single sign-on (SSO) in CloudCampus networks.

2. Network O&M → Infrastructure API

The Infrastructure API provides tools for network monitoring, diagnostics, and automated management.

It is used for:

Device status monitoring

Network topology visualization

Fault detection and real-time alerts

Performance optimization

3. LBS (Location-Based Services) → LBS API

The LBS API enables applications to access location data collected by the network.

It is used for:

Tracking users or assets within a campus network

Heatmap generation and movement analytics

Geo-fencing and location-based policies

4. Crowd profiling → VAS API

VAS (Value-Added Services) API is designed for advanced analytics and business intelligence.

It supports:

User behavior analytics

Demographic profiling

Marketing strategies based on network usage patterns

Reference from Huawei HCIE-Datacom Documentation:

HCIE-Datacom Training Guide – CloudCampus Solution

Huawei iMaster NCE-Campus API Documentation

Huawei CloudCampus Solution Whitepaper – Open API and Use Cases

Comprehensive and Detailed Explanation:

In the given configuration:

Traffic from PC1 (192.168.1.1) is classified by ACL 2000.

Traffic is remarked with DSCP value 26 (DSCP 26).

DSCP 26 corresponds to AF31, which maps to the AF3 queue in DiffServ QoS.

DiffServ QoS Queue Mapping:

EF (Expedited Forwarding) → DSCP 46

AF4 (Assured Forwarding Class 4) → DSCP 40-47

AF3 (Assured Forwarding Class 3) → DSCP 26-31 ✅

AF2 (Assured Forwarding Class 2) → DSCP 18-23

Since DSCP 26 falls within AF3, the packets enter the AF3 queue on R2.

???? Reference: Huawei HCIE Datacom – QoS and DSCP Mapping

In MPLS LDP (Label Distribution Protocol), label retention modes control how labels are stored in the Label Forwarding Information Base (LFIB).

DU Label Advertisement Mode (Downstream Unsolicited):

Labels are advertised to all LDP peers without a request.

The receiving router decides which label to use for forwarding.

Liberal vs. Conservative Label Retention:

✅ Liberal Label Retention Mode (Correct Answer)

All received labels from all LDP peers are stored.

Even if a peer is not the optimal next hop, its label is retained.

Allows faster convergence during failures.

❌ Conservative Label Retention Mode

Only the label from the best next-hop peer is stored.

Reduces memory usage but can slow down convergence in case of failure.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS LDP Configuration Guide – Liberal vs. Conservative Label Retention

HCIE-Datacom Training Material – Label Advertisement in MPLS Networks

The Time-To-Live (TTL) field in MPLS is essential for preventing infinite loops and enhancing security.

MPLS TTL Field Functionality:

It prevents packets from circulating indefinitely in the MPLS network.

It allows traceroute (tracert) to identify MPLS hops when TTL propagation is enabled.

Explanation of Correct Answers:✅ B. The processing of IP TTL copy hides the LSR in an MPLS domain, improving security.

If TTL propagation is disabled, MPLS routers do not decrease TTL, hiding internal LSRs from traceroute, enhancing security.

✅ C. MPLS provides two TTL processing modes:

Default Mode: The MPLS TTL copies the IP TTL value when an IP packet enters the MPLS network.

Uniform Mode: The ingress LER sets the MPLS TTL to 255, so it does not decrement.

✅ D. MPLS encapsulation in frame mode supports the TTL field, while cell mode does not.

Frame Mode (Ethernet, PPP, etc.) supports TTL.

Cell Mode (ATM/MPLS) does not support TTL.

Incorrect Answer Explanation:❌ A. If TTL copy is disabled, users can use the tracert function to view MPLS hops.

Wrong! If TTL propagation is disabled, tracert cannot see LSRs inside the MPLS core network.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – TTL Field & Loop Prevention

HCIE-Datacom MPLS VPN Configuration Guide – Traceroute in MPLS Networks

Understanding Huawei SD-WAN VN (Virtual Network) Topologies

Huawei SD-WAN uses Virtual Networks (VNs) to provide traffic isolation and policy-based routing for different services, branches, and applications.

???? VN Topologies Can Be Different

Each VN (Virtual Network) can have its own topology.

Some VNs may use full-mesh, while others may use hub-and-spoke or star topology.

Different VNs can have different routing and security policies.

✅ Example:

Corporate traffic (VN1) → Full-mesh topology for efficient inter-branch communication.

Guest Wi-Fi traffic (VN2) → Hub-and-spoke topology to restrict inter-site communication.

Why is the Answer FALSE?

❌ All VNs do not have to use the same topology.✅ Each VN can be configured independently with a unique topology, routing policy, and security settings.

✅ Reference: Huawei HCIE-Datacom Guide – SD-WAN VN Topologies and Segmentation

Understanding SSH Authentication and Key Exchange

???? What Happens When an SSH Client Connects to a Server?1️⃣ Key Exchange Phase (KEX)

Even if only password authentication is used, SSH still performs key exchange.

The server and client negotiate encryption keys using algorithms like Diffie-Hellman (DH).

2️⃣ User Authentication Phase

After encryption keys are exchanged, the user authenticates using a username and password.

Why is the Answer FALSE?

❌ Even with password authentication, SSH still performs key exchange to establish an encrypted session.✅ The SSH session is always encrypted using cryptographic keys generated during KEX.

Real-World Application:

Secure Remote Access: Protects login credentials from MITM (Man-in-the-Middle) attacks.

Cloud & Datacenter Networks: Ensures secure SSH connections across remote infrastructure.

✅ Reference: Huawei HCIE-Datacom Guide – SSH Key Exchange and Authentication

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.

References:

Huawei HCIE Datacom V3.0 Training Materials, Sections 4.2, 4.3, and 5 – Spanning Tree Protocol, Loop Prevention, and Switch Performance.

Huawei Official Documentation on Ethernet Switching and Loop Management, available in HCIE Datacom Certification Guides (2023 update).

OSPFv3 (for IPv6) introduces significant changes compared to OSPFv2 (for IPv4).While both versions share similar routing mechanisms, there are key LSA format and functional differences beyond just address changes.

Major Differences Between OSPFv2 and OSPFv3:

Address Independence (LSA Format Changes)

OSPFv3 LSAs do not contain IP addresses directly; they rely on Link-LSA and Intra-Area Prefix LSA to advertise addresses.

In OSPFv2, IP addresses were included in LSA headers.

New LSA Types in OSPFv3

LSA Type 8 (Link-LSA): Advertises a router’s IPv6 address to neighbors.

LSA Type 9 (Intra-Area Prefix LSA): Replaces the address information in Router-LSAs and Network-LSAs.

Support for Multiple Address Families (AF)

OSPFv3 can support both IPv4 and IPv6 in newer implementations (RFC 5838).

Authentication Mechanism Removed

OSPFv3 relies on IPsec for authentication, whereas OSPFv2 had built-in authentication mechanisms.

Incorrect Statement Explanation:

❌ The statement "LSA formats and functions remain unchanged" is false because:

LSA structures were modified in OSPFv3.

New LSA types were introduced to handle IPv6 addresses separately.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPFv3 Configuration Guide – LSA Differences from OSPFv2

HCIE-Datacom Study Material – OSPFv3 Evolution & IPv6 Implementation

VRRP (Virtual Router Redundancy Protocol) and Flapping

VRRP ensures gateway redundancy by allowing multiple routers to work together as a virtual router. Flapping occurs when the master and backup routers frequently switch roles.

Causes of VRRP Flapping:

✅ A. Too small interval between Advertisement packet transmissions – Can cause flapping

If the Advertisement interval is too short, frequent VRRP state changes can occur.

✅ C. Packet loss on an interface of the backup device – Can cause flapping

If the backup router loses VRRP packets, it might assume the master is down and initiate an election.

✅ D. Flapping on the link transmitting VRRP Advertisement packets – Can cause flapping

If the link used for VRRP experiences instability, packets may be lost, triggering VRRP role changes.

Incorrect Answer Explanation:

❌ B. Inconsistent preemption delay settings – Does NOT cause VRRP flapping

Preemption delay only affects when a router takes over as master after recovering from a failure.

It does not directly cause flapping because the role change happens only after a delay, preventing frequent transitions.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VRRP Configuration Guide – Preventing VRRP Flapping

HCIE-Datacom Study Material – VRRP Timers and Stability

Analyzing the Routing Table Output:

The command display ipv6 routing-table protocol isis shows all IPv6 routes learned via IS-IS.

The output shows "Summary Count: 6", meaning R1 has six IS-IS IPv6 routes.

Explanation of Correct Answers:✅ A. R1 has six IS-IS IPv6 routes.

The "Summary Count: 6" confirms that six IS-IS IPv6 routes exist in R1's routing table.

✅ C. IS-IS IPv6 must have been enabled on GigabitEthernet0/0/1 of R1.

The interface GigabitEthernet0/0/1 is listed as the next-hop, meaning IS-IS IPv6 must be enabled on that interface.

✅ D. R1 is not a Level-1 device.

The protocol is listed as "ISIS-L2", indicating that R1 is an IS-IS Level-2 (backbone) router, not a Level-1 router.

Incorrect Answer Explanation:❌ B. R1 does not have IS-IS IPv6 routes.

Wrong! The output clearly shows six IS-IS IPv6 routes, proving this statement false.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPv6 Routing Protocols Guide – IS-IS for IPv6

HCIE-Datacom Routing & Switching Training – IS-IS L1 & L2 Operations

Huawei IS-IS Configuration Guide – IPv6 Route Management

Understanding EVPN (Ethernet VPN) Label Allocation and ARP Handling

???? What Happens in This Scenario?1️⃣ CE1 (192.168.1.1) sends an ARP request to discover the MAC address of CE2 (192.168.1.2).2️⃣ PE1 receives the ARP request and needs to forward it over the EVPN fabric.3️⃣ To send the broadcast ARP request across the EVPN network, PE1 forwards the packet to PE4 using BUM (Broadcast, Unknown unicast, and Multicast) forwarding.4️⃣ PE4, as the Designated Forwarder (DF), forwards the ARP request to CE2.

Role of Labels in EVPN VXLAN/MPLS Networks

???? EVPN uses BGP to distribute MAC/IP reachability information using different route types.

✅ EVPN Type 2 Route (MAC/IP Advertisement Route):

Used for MAC-to-IP address mapping announcements.

Ensures remote VTEPs (PE routers) learn MAC-to-IP bindings dynamically.

✅ EVPN Type 3 Route (Inclusive Multicast Route):

Used for BUM traffic (Broadcast, Unknown Unicast, Multicast).

Assigns a multicast label (e.g., 201) to be used for forwarding broadcast packets like ARP requests.

???? In this case:

The label 201 is used for BUM traffic forwarding.

BUM traffic is handled using an EVPN Type 3 route.

Why is the Answer 3?

✅ EVPN Type 3 routes carry labels for BUM traffic, which includes ARP requests.✅ Label 201 is used for multicast distribution, which is managed by Type 3 routes.

Real-World Application:

VXLAN Data Centers: Uses EVPN Type 3 routes to control BUM traffic efficiently.

Campus Networks: Prevents unnecessary flooding of ARP requests across VXLAN domains.

✅ Reference: Huawei HCIE-Datacom Guide – EVPN BGP Route Types and Multicast Labeling

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

Forwarding Equivalence Class (FEC) is a key concept in MPLS (Multiprotocol Label Switching), where packets with the same forwarding characteristics are grouped into an FEC and assigned a label.

Correct Answers (Cannot be Used for FEC Allocation):

A. Fragment Offset – Incorrect as an FEC allocation standard

Fragment offset is used for reassembling fragmented IP packets at the receiver side.

It is not relevant for MPLS label assignment.

B. Application Protocol – Incorrect as an FEC allocation standard

MPLS does not classify packets based on application-layer protocols (e.g., HTTP, FTP).

It works mainly at Layer 2 and Layer 3.

Incorrect Answers (Valid FEC Allocation Standards):

C. Destination Address – Valid FEC allocation criterion

One of the most common MPLS FEC classifications.

Packets with the same destination are grouped into the same FEC.

D. Class of Service (CoS) – Valid FEC allocation criterion

MPLS uses CoS-based traffic classification (e.g., Exp bits in MPLS headers).

Different CoS levels can be mapped to different labels.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – FEC and Label Assignment

HCIE-Datacom MPLS VPN Configuration Guide

Understanding HTTP Security Risks

???? What is HTTP?

HTTP (Hypertext Transfer Protocol) is a protocol used for communication between web clients (browsers) and servers.

It is unencrypted, making it vulnerable to security threats.

Potential Risks in HTTP Communication:

✅ A. Eavesdropping (Data Interception)

Correct: HTTP traffic is unencrypted, meaning attackers can capture data using tools like Wireshark or MITM (Man-in-the-Middle) attacks.

Example: Hackers intercept login credentials over public Wi-Fi.

✅ B. Pretending (Impersonation / Spoofing)

Correct: Without encryption or authentication, attackers can spoof legitimate websites.

Example: A phishing website mimics a banking login page to steal user credentials.

✅ C. Tampering (Data Manipulation)

Correct: Attackers can modify HTTP data in transit, changing the content sent to users.

Example: Injecting malicious scripts into a webpage (e.g., Cross-Site Scripting - XSS).

❌ D. Lost (Low Probability of Data Loss)

Incorrect: HTTP runs over TCP, which ensures reliable data transmission.

Packet loss is not a major security risk but rather a network performance issue.

How to Mitigate HTTP Risks?

Use HTTPS (HTTP Secure) → Encrypts data using TLS (Transport Layer Security).

Enable HSTS (HTTP Strict Transport Security) → Forces HTTPS connections.

Implement Web Application Firewalls (WAFs) → Protects against attacks like SQL Injection & XSS.

✅ Reference: Huawei HCIE-Datacom Guide – Network Security Risks in HTTP Communication