Huawei H12-891_V1.0 HCIE-Datacom V1.0 Exam Practice Test

Comprehensive and Detailed Explanation:

✔ 802.1X authentication supports multiple logout mechanisms based on network conditions and security policies.

✔ Correct Logout Modes:✅ (A) Authentication Server Logout → The RADIUS server can terminate a session.✅ (B) Manual Logout → Users can disconnect manually.✅ (C) Access Device Logout → The switch/WLAN controller can enforce logouts (e.g., if inactivity is detected).

✔ Why Not (D)?❌ (D) Accounting Server Logout → The accounting server tracks session usage but does not enforce logouts.

???? Reference: Huawei HCIE Datacom – 802.1X Authentication & Session Termination

Telemetry Data Collection in Huawei Devices

Telemetry allows real-time streaming of network performance data based on predefined sampling paths. Supported sampling paths include:

✅ A. Interface statistics

Monitors real-time traffic usage, errors, and packet loss on interfaces.

✅ C. CPU information

Tracks CPU utilization and performance metrics.

✅ D. Memory information

Monitors RAM usage and system memory consumption.

Incorrect Answer:

❌ B. Information about the optical module on an interface

Telemetry does not natively support direct optical module monitoring; instead, SNMP or CLI commands like display transceiver are used.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Supported Sampling Paths

HCIE-Datacom Study Material – Network Performance Monitoring with Telemetry

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).

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

Comprehensive and Detailed Explanation:

The display current-configuration command is used to show the active running configuration stored in RAM (memory).

Key Features:

✔ Displays current settings for interfaces, routing, and security.✔ Reflects real-time changes (different from startup-config stored in NVRAM).✔ Useful for troubleshooting and verification before saving configurations.

Thus, the statement is TRUE.

???? Reference: Huawei HCIE Datacom – Command Reference Guide

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

Understanding IPsec SA (Security Association) Establishment

???? IPsec (IP Security) provides encrypted communication over IP networks.???? Security Associations (SAs) define encryption, authentication, and key parameters for IPsec tunnels.

Two IPsec SA Modes:

1️⃣ Manual Mode:

All parameters (keys, encryption methods, authentication settings) must be manually configured.

Keys do not change automatically, making it less secure.

2️⃣ IKE (Internet Key Exchange) Auto-Negotiation Mode:

Uses IKE Phase 1 and Phase 2 to automatically negotiate, generate, and exchange keys.

Keys are periodically refreshed, increasing security.

Uses Diffie-Hellman (DH) key exchange for secure key generation.

Why is Answer D Incorrect?

❌ D. SAs established in both manual and IKE auto-negotiation modes can be dynamically updated.

Incorrect: In manual mode, the IPsec SA is static and does not support dynamic updates.

Correct behavior: Only IKE auto-negotiation mode supports dynamic re-keying and SA updates.

✅ Reference: Huawei HCIE-Datacom Guide – IPsec SA Modes and IKE Negotiation

Understanding Huawei CloudCampus Access Control

Huawei’s CloudCampus solution provides centralized authentication and policy management via iMaster NCE-Campus.

???? Analysis of Each Option:

✅ A. iMaster NCE can function as an authentication server.

Correct: iMaster NCE includes AAA (Authentication, Authorization, and Accounting) capabilities, reducing dependency on external servers.

❌ B. Cloud APs support local Portal authentication.

Incorrect: Huawei Cloud APs do NOT support local Portal authentication.

Instead, Portal authentication is managed centrally by iMaster NCE, NOT by individual APs.

✅ C. iMaster NCE can function as a Portal relay device.

Correct: It can relay authentication requests to a RADIUS or AAA server.

✅ D. iMaster NCE can interconnect with a third-party RADIUS server.

Correct: It supports integration with external RADIUS authentication servers for enterprise authentication.

Real-World Application:

Used in Wi-Fi 6 enterprise deployments where centralized authentication, security, and policy enforcement are needed.

✅ Reference: Huawei HCIE-Datacom Guide – CloudCampus Authentication Architecture

Comprehensive and Detailed Explanation:

✔ Analyzing the Python Code:✅ (A) Correct → print(r.json()) prints the response JSON, showing the token ID.✅ (B) Correct → The token request URL is correctly specified.✅ (D) Correct → json={"userName": nbi_name, "password": nbi_pwd} confirms the request body is in JSON format.

❌ (C) Incorrect:

The request uses POST, not GET (requests.post() is explicitly called).

???? Reference: Huawei HCIE Datacom – RESTful API Authentication in iMaster NCE

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

Comprehensive and Detailed Explanation:

6PE (IPv6 Provider Edge) and 6VPE (IPv6 VPN Provider Edge) allow IPv6 traffic over an MPLS network, but they differ in VPN support and address isolation.

Comparison of 6PE vs. 6VPE:

A screenshot of a computer AI-generated content may be incorrect.

Since 6VPE supports VRFs, it allows IPv6 address reuse for different VPN customers.Thus, the correct answer is A.

???? Reference: Huawei HCIE Datacom – 6PE and 6VPE Implementation

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.

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

Congestion Avoidance in Networking

Congestion avoidance mechanisms prevent packet loss and delay by managing queues before congestion occurs.

Common Congestion Avoidance Techniques:

Weighted Random Early Detection (WRED) – Randomly drops low-priority packets before congestion builds up.

Explicit Congestion Notification (ECN) – Marks packets instead of dropping them to signal congestion.

Queue Management – Techniques like priority queuing (PQ) and weighted fair queuing (WFQ) help prevent congestion.

Reference from Huawei HCIE-Datacom Documentation:

Huawei QoS Configuration Guide – Congestion Avoidance Technologies

HCIE-Datacom Study Material – Traffic Management and Queue Optimization

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

Comprehensive and Detailed Explanation:

✔ iMaster NCE-WAN provides a RESTful API for integration with third-party applications and network automation platforms.

✔ Why RESTful API?

Uses HTTP/HTTPS for communication.

Supports JSON and XML data formats.

Enables orchestration, monitoring, and automation.

✔ Why Not Other Options?❌ (A) NETCONF → Used for device-level configuration, not northbound APIs.❌ (B) SNMP → Used for network monitoring, not northbound integration.❌ (C) CLI → Used for manual command execution, not API communication.

???? Reference: Huawei HCIE Datacom – iMaster NCE-WAN Northbound API

Network Slicing Using Channelized Sub-Interfaces and FlexE

Both channelized sub-interfaces and FlexE (Flexible Ethernet) are used for network slicing, but they have different application scenarios:

✅ A. Channelized sub-interface is recommended for interfaces with bandwidth < 50 Gbit/s.

Channelized sub-interfaces split a physical interface into multiple logical sub-interfaces.

Best for lower-bandwidth links (<50 Gbit/s).

✅ B. FlexE is recommended for 50GE and higher-rate interfaces.

FlexE divides a high-bandwidth physical link (e.g., 100GE, 400GE) into multiple virtual slices.

Used in high-speed backbone and data center networks.

✅ C. Only FlexE-based network slicing can be deployed across OTN devices.

FlexE is compatible with Optical Transport Network (OTN) and can be used for long-haul slicing across OTN.

❌ D. Only channelized sub-interface-based network slicing can be deployed across MSTP devices.

Incorrect! While MSTP supports channelized interfaces, FlexE is not restricted to MSTP deployment.

Reference from Huawei HCIE-Datacom Documentation:

Huawei FlexE Technology Whitepaper – Network Slicing in Transport Networks

HCIE-Datacom Training Material – Channelized Sub-Interface and FlexE in Network Slicing

Comprehensive and Detailed Explanation:

Port isolation is a feature used to enhance security and network segmentation by restricting communication between certain switch ports at Layer 2 while allowing them to communicate through Layer 3.

Layer 2 Communication: Devices within the same VLAN can communicate with an upstream gateway or router.

Layer 3 Isolation: Devices cannot communicate directly at Layer 2 but must pass through a Layer 3 device (e.g., a router or firewall).

Use Case: Typically used in enterprise networks, hotel networks, and campus networks to prevent unwanted direct communication between clients.

Thus, the statement is correct, and the answer is TRUE.

???? Reference: Huawei HCIE Datacom Official Guide - Ethernet Port Isolation

Understanding Network Security for Authorized User Access

???? Problem Scenario:

Only authorized users should be allowed network access.

Users can obtain IP addresses either via DHCP or a predefined static IP list.

Unauthorized users (e.g., attackers using rogue DHCP servers or spoofed IPs) must be blocked.

???? Required Technologies for Securing Access:1️⃣ DHCP Snooping – Protects against rogue DHCP servers and builds a binding table of legitimate DHCP clients.2️⃣ IP Source Guard (IPSG) – Ensures that only authorized IP-MAC bindings can send traffic.

Analysis of the Answer Choices:

❌ A. DAI + Port Security (Incorrect)

DAI (Dynamic ARP Inspection) prevents ARP spoofing but does not validate IP-MAC-DHCP bindings.

Port Security only limits MAC addresses per port but does not verify IP addresses.

Does NOT protect against unauthorized static IP users.

✅ B. DHCP Snooping + IPSG (Correct)

DHCP Snooping:

Prevents rogue DHCP servers from assigning unauthorized IPs.

Builds a DHCP binding table (IP-MAC-Port).

IP Source Guard (IPSG):

Blocks traffic from IPs not listed in the DHCP snooping binding table.

Can be configured to allow manually specified static IP addresses.

Best choice to allow only authorized users (both DHCP and static IP users).

❌ C. DHCP Snooping + DAI (Incorrect)

DAI (Dynamic ARP Inspection) prevents ARP spoofing but does not block unauthorized static IP users.

Lacks IP-level access control needed to enforce static IP policies.

❌ D. DAI + IPSG (Incorrect)

IPSG (IP Source Guard) needs DHCP Snooping to build the binding table.

Without DHCP Snooping, IPSG cannot function properly.

DAI does not provide complete protection against unauthorized users.

Why is the Answer B (DHCP Snooping + IPSG)?

✅ Ensures only users assigned a DHCP IP (or authorized static IPs) can send traffic.✅ Blocks rogue DHCP servers and unauthorized static IP users.

Real-World Application:

Enterprise Networks: Prevents unauthorized static IP users or attackers from accessing VLANs.

Public Wi-Fi Security: Ensures only authorized users receive IPs and can send traffic.

✅ Reference: Huawei HCIE-Datacom Guide – DHCP Snooping and IPSG Security Mechanisms

Huawei SD-WAN supports various intelligent traffic steering mechanisms to optimize link utilization and balance network traffic across multiple links.

✅ D. Traffic bandwidth-based traffic steering

This method ensures that traffic is distributed across multiple links based on available bandwidth.

SD-WAN dynamically selects links based on their real-time bandwidth utilization, ensuring optimal performance and load balancing.

Understanding the Telemetry Output:

Dest-addr: 192.168.56.1 → The destination IP address is 192.168.56.1. ✅

Dest-name: Dest1 → The destination group name is Dest1. ✅

Protocol: gRPC → Data push uses the gRPC protocol. ✅

Vpn-name: - (empty) → No VPN encapsulation is used. ❌

Incorrect Answer Explanation:

❌ C. "VPN encapsulation is used for data push" → Incorrect!

The Vpn-name field is empty, indicating that VPN encapsulation is NOT enabled for telemetry data transport.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Destination and Data Push Methods

HCIE-Datacom Study Material – gRPC and Telemetry Data Streaming

Comprehensive and Detailed Explanation:

The Huawei Registration Query Center allows devices to register and go online automatically in a cloud-managed environment.

✔ Supported Devices:

Switches ✅

Access Routers (AR) ✅

Access Points (APs) ✅

Firewalls ✅

✔ How It Works:

Devices obtain their registration information via DHCP Option 148 or pre-configured credentials.

The devices then connect to the registration query center to retrieve configuration and authentication details.

Once authenticated, they go online and become manageable via iMaster NCE-Campus.

???? Reference: Huawei HCIE Datacom – CloudCampus Device Registration

OSPFv3 (IPv6 OSPF) introduces modified LSA types compared to OSPFv2.

AS-external-LSAs (Type 5):

Used for advertising external routes (outside the OSPF domain).

Flooded across the entire OSPF AS (except stub areas).

Other LSAs:

Link-LSA (Type 8): Local to the link.

Inter-Area-Prefix-LSA (Type 3): Used for inter-area route distribution.

Intra-Area-Prefix-LSA (Type 9): Used within a single OSPF area.

✅ Reference: Huawei HCIE-Datacom Guide - OSPFv3 LSA Types

Comprehensive and Detailed Explanation:

✔ Hub-Spoke networking is the most efficient and scalable model for interconnecting 100+ branches in a small and midsize campus network.

✔ Why Hub-Spoke?

Centralized Control: A hub router manages communication between spoke routers (branch sites).

Reduced Complexity: Unlike full-mesh, which requires N(N-1)/2* connections, hub-spoke minimizes link costs.

Easier Management: Policy enforcement and security are centralized at the hub site.

✔ Why Not Other Options?❌ A (Direct Networking) → Suitable for small networks, but inefficient for 100+ branches.❌ B (Full-Mesh Networking) → High cost and complexity, requiring too many links.❌ D (Partial-Mesh Networking) → More scalable than full-mesh, but hub-spoke is more optimized for large branch networks.

???? Reference: Huawei HCIE Datacom – WAN Interconnection Models

Traffic Diversion in SR-MPLS Policy

SR-MPLS Policies use traffic steering mechanisms to direct specific flows to Segment Routing paths (SR Policies). When multiple services share the same destination address, color-based traffic diversion ensures differentiated service treatment.

✅ B. Color-based traffic diversion (Correct Answer)

Traffic is classified based on "color" (a BGP-SR policy attribute) and mapped to different SR-MPLS tunnels.

Different colors represent different paths (e.g., high-priority services can use an optimized low-latency path).

This method ensures service quality by directing traffic according to policy-based routing decisions.

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 Inter-AS MPLS VPN Option C (Solution 2)

In MPLS L3VPN Inter-AS Option C, the Route Reflectors (RRs) are used for VPN route distribution but do not participate in data forwarding. The traffic forwarding path is based on MPLS labels assigned at different routers.

Each data packet carries two MPLS labels:

Transport Label (T1) – Used for forwarding within the backbone.

VPN Label (V1) – Used for VPN route identification.

Breaking Down the Labels:

✔ VPN Label (V1) – Allocated by PE1 (Answer: C ✅)

V1 (Inner Label) is the VPN label assigned by the egress PE router (PE1).

This label ensures that when the packet reaches PE1, it knows how to forward the traffic to CE1 (192.168.1.1).

✔ Transport Label (T1) – Allocated by P2 (Answer: B ✅)

T1 (Outer Label) is the transport label assigned by P2 to forward the packet across the AS core.

This label ensures the packet reaches the next-hop router (ASBR-PE1 in AS100).

Why Are the Other Options Incorrect?

❌ A. "T1 is allocated by RR2" (Incorrect)

RR2 is used only for route reflection; it does not participate in label allocation or forwarding.

❌ D. "V1 is allocated by P2" (Incorrect)

P2 is an intermediate router and does not allocate VPN labels.

VPN labels are always assigned by the egress PE router (PE1 in AS100).

???? Reference: Huawei HCIE Datacom – MPLS L3VPN Inter-AS Option C

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

Comprehensive and Detailed Explanation:

OSPFv2 (for IPv4) and OSPFv3 (for IPv6) LSAs differ in function and naming conventions.

Key Differences in OSPFv3 LSAs:

OSPFv3 does not use ASBR-Summary-LSA. Instead, it introduces new Inter-Area Prefix LSAs (Type 3) and Inter-Area Router LSAs (Type 4).

OSPFv2 ASBR-Summary-LSA (Type 4) is replaced in OSPFv3 by Inter-Area Router LSA (Type 4).

OSPFv3 LSA Types:

✔ Router-LSA (Type 1) – Describes router interfaces and links.✔ Network-LSA (Type 2) – Describes broadcast network links.✔ Inter-Area Prefix LSA (Type 3) – Replaces Summary LSAs for routes.✔ Inter-Area Router LSA (Type 4) – Replaces ASBR Summary LSAs.✔ AS-External LSA (Type 5) – Describes external routes (same as OSPFv2).

Since ASBR-Summary-LSA (Type 4) does not exist in OSPFv3, the correct answer is A.

???? Reference: Huawei HCIE Datacom – OSPFv3 LSA Types

Understanding Route Reflectors (RRs) in Huawei SD-WAN

In Huawei’s SD-WAN Solution, BGP Route Reflectors (RRs) are used to reduce the number of BGP peer relationships and optimize routing scalability.

???? Key Functions of an RR in SD-WAN:

Centralizes BGP route distribution in large-scale SD-WAN networks.

Reduces full-mesh BGP peering complexity.

Improves network scalability and convergence time.

Analysis of Each Deployment Mode:

✅ B. Independent deployment of the RR

Correct: The RR is deployed as a standalone device, independent of the SD-WAN hub site.

Best for large-scale SD-WAN deployments requiring dedicated route control.

✅ C. Co-deployment of the RR and hub site

Correct: The RR is co-located with the SD-WAN hub site, reducing infrastructure overhead.

Best for mid-sized SD-WAN deployments where the hub and RR functions can be combined.

✅ D. Partially independent deployment of the RR

Correct: The RR is partially separated from the hub but still shares some resources.

Provides a balance between full independence and co-location.

❌ A. Multi-area deployment of the RR (Incorrect Choice)

Multi-area RR deployment is not a common Huawei SD-WAN practice.

Huawei does not require separate RRs per area, as SD-WAN is based on centralized policy-based routing.

Real-World Application:

Large Enterprise SD-WAN: Uses independent RRs to optimize global network routing.

Service Provider SD-WAN: Uses co-deployed RRs to reduce infrastructure costs while maintaining route scalability.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Route Reflectors in SD-WAN Architecture

Understanding VXLAN and BGP EVPN Control Plane

VXLAN (Virtual eXtensible LAN) is an overlay network technology that enables Layer 2 (L2) extension over an IP-based network using MAC-in-UDP encapsulation.

???? Traditional VXLAN Flooding Issue:

Without BGP EVPN, VXLAN uses flood-and-learn behavior for MAC address learning.

Broadcast, Unknown Unicast, and Multicast (BUM) traffic is flooded to all VTEPs, which is inefficient.

???? How Does BGP EVPN Solve Flooding?

BGP EVPN (Ethernet VPN) replaces the flood-and-learn model with a distributed control plane.

MAC/IP bindings are advertised through BGP EVPN Type 2 routes, eliminating the need for flooding ARP requests.

VXLAN routers learn MAC addresses proactively instead of relying on flooding.

Why is the Answer TRUE?

✅ BGP EVPN fully prevents ARP flooding by distributing MAC/IP bindings via control plane updates.✅ VTEPs only send traffic to known destinations, reducing network congestion.✅ BGP EVPN is the industry standard for large-scale data center and campus VXLAN deployments.

Real-World Application:

Data Centers: Avoids unnecessary ARP request flooding in large cloud networks.

Campus Networks: Reduces L2 broadcast storms, improving network efficiency.

Service Provider Networks: Enables scalable multi-tenant VXLAN solutions.

✅ Reference: Huawei HCIE-Datacom Guide – VXLAN BGP EVPN Control Plane Architecture

Route Target (RT) is a BGP extended community attribute used in MPLS Layer 3 VPNs (L3VPNs) to control the import and export of VPN routes between different VPN instances (VRFs).

Explanation of Correct Answers:

✅ A. Each VPN instance is associated with one or more pairs of VPN Target attributes, used to control VPN routing information advertisement and reception between sites.

Each VRF (VPN Routing and Forwarding instance) has an associated RT that determines which routes are imported and exported between VPNs.

RTs enable inter-VPN communication while maintaining separation between VPN customers.

✅ B. Export Target and Import Target are independent of each other and support multiple values to implement flexible VPN routing information advertisement and reception control.

The Export RT specifies which routes should be advertised.

The Import RT specifies which routes should be accepted into a VRF.

These can be configured independently to control traffic flow between VPNs.

✅ C. RTs are classified into two types: Export Target and Import Target.

Export Target: Defines which VPN routes are advertised.

Import Target: Defines which VPN routes are accepted.

A VPN instance can have multiple RTs to allow flexibility.

✅ D. The RT value is advertised to neighbors through the BGP extended community attribute in Update messages.

RTs are carried in BGP UPDATE messages as part of the BGP extended community attribute, enabling VPN route exchange between PEs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Route Target (RT) Concepts

HCIE-Datacom Study Material – BGP Route Advertisement in MPLS VPNs

Comprehensive and Detailed Explanation:

✔ IPsec uses a hybrid encryption approach:

Asymmetric encryption (e.g., RSA, DH) secures the symmetric key exchange.

Symmetric encryption (e.g., AES, 3DES) is then used to encrypt actual data.

✔ Why This is Secure?

Asymmetric encryption ensures key confidentiality between peers.

Symmetric encryption ensures high-performance encryption for bulk data.

???? Reference: Huawei HCIE Datacom – IPsec Encryption Mechanisms

Understanding 6PE & 6VPE in MPLS Networks

6PE (IPv6 Provider Edge) and 6VPE (IPv6 VPN Provider Edge) are MPLS-based solutions that allow IPv6 traffic to be carried over an MPLS IPv4 core network without requiring the entire backbone to support IPv6.

???? 6PE (IPv6 over MPLS - No VPN)

Used for global IPv6 routing without VPN segmentation.

No need for VRFs (VPN Routing and Forwarding instances) because IPv6 prefixes are handled natively.

???? 6VPE (IPv6 VPN over MPLS - Supports VPNs)

Extends MPLS L3VPN to support IPv6 routing inside VPN instances.

Uses MP-BGP VPNv6 to distribute IPv6 prefixes inside MPLS VPNs.

Why is the Answer TRUE?

✅ No VRFs are required for 6PE:

6PE only needs BGP labeled IPv6 routes in the global routing table.

IPv6 prefixes are carried using MPLS labels without VPN segmentation.

✅ VRFs are required for 6VPE, NOT for 6PE:

6VPE requires VPN instances (VRFs) for IPv6 L3VPNs, but 6PE does not.

✅ Real-World Application:

6PE is used in large ISP networks where IPv6 deployment is needed but without VPN separation.

6VPE is used for enterprise MPLS VPNs, allowing customers to have isolated IPv6 routing tables.

✅ Reference: Huawei HCIE-Datacom Guide – MPLS IPv6 Transition Technologies (6PE & 6VPE)

Understanding BFD (Bidirectional Forwarding Detection)

BFD is a high-speed fault detection protocol used to monitor link failures in milliseconds.

It operates at Layer 2 (Data Link Layer) and Layer 3 (Network Layer) to provide fast convergence.

Why Can BFD Detect Failures in Milliseconds?

Uses lightweight control packets that are exchanged between routers.

Works with OSPF, IS-IS, BGP, and MPLS to trigger fast convergence.

Detection time = (Transmit Interval) × (Detect Multiplier)

Example: If the interval is 3ms and the multiplier is 3, failure detection takes 9ms.

Why is the Answer TRUE?

✅ BFD achieves millisecond-level detection by sending rapid probe packets.✅ Used in high-availability networks where link failures must be detected in real-time.

Real-World Application

Service Provider Networks: BFD improves network resilience by detecting link failures faster than traditional routing timers.

Enterprise WANs: Used in SD-WANs to switch paths dynamically.

MPLS Fast Reroute (FRR): Works with MPLS Traffic Engineering for near-instantaneous failover.

✅ Reference: Huawei HCIE-Datacom Guide – BFD for Fast Link Failure Detection

In firewall hot standby (HRP - Hot Standby Routing Protocol) mode, certain data can be synchronized between the active and standby firewalls to ensure uninterrupted service.

The following data is backed up:

✅ Server mapping table: Contains information about NAT mappings and other session mappings.

✅ AAA user table (excluding the default user admin): Ensures that authenticated users do not need to re-authenticate in case of failover.

✅ Session table: Ensures that existing connections remain active when switching to the standby firewall.

❌ Dynamic MAC address table is NOT backed up because it is dynamically learned and not relevant to firewall session synchronization.

✅ Reference: Huawei HCIE-Datacom Guide - Firewall HRP Synchronization

Comprehensive and Detailed Explanation:

✔ MPLS labels in SR-MPLS are calculated using the SRGB (Segment Routing Global Block) base and the Prefix-SID.

✔ Label Calculation Formula:

MPLS Label=SRGB Base+Prefix-SID\text{MPLS Label} = \text{SRGB Base} + \text{Prefix-SID}MPLS Label=SRGB Base+Prefix-SID

✔ Extracting Values from the LSDB:

SRGB Base: 36000

Prefix-SID: 300

✔ Valid MPLS Labels:

36000 + 300 = 36300

40002 and 38002 fall within the SRGB range.

39002 is outside the expected range, making it the incorrect answer.

???? Reference: Huawei HCIE Datacom – Segment Routing Label Calculation

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:

Key Factors Affecting FTP Performance:

Tail Drop and TCP Synchronization (A) ✅

Tail Drop causes TCP global synchronization, reducing FTP speeds drastically when congestion occurs.

Since FTP is TCP-based, packet loss due to tail drop forces TCP retransmissions, further degrading performance.

Priority Preemption by Video Traffic (D) ✅

UDP-based real-time video traffic is often prioritized over TCP-based traffic to avoid jitter and packet loss.

If video traffic has higher QoS priority, FTP bandwidth may be preempted, leading to slow speeds.

Incorrect Options:

❌ Option B: PQ scheduling typically prioritizes latency-sensitive traffic (VoIP), but this scenario does not mention priority queuing for FTP.❌ Option C: No information about an explicit rate limit on FTP traffic.

???? Reference: Huawei HCIE Datacom – QoS and Congestion Control

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

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

Comprehensive and Detailed Explanation:

✔ All four egress modes are supported in Huawei CloudCampus Virtualized Fabric to provide flexibility in connecting external networks.

✔ Modes Explained:✅ Layer 3 Shared Egress → Multiple VNs share a single Layer 3 gateway for external communication.✅ Layer 2 Shared Egress → Multiple VNs share the same Layer 2 link to the external network.✅ Layer 3 Exclusive Egress → Each VN has its own separate Layer 3 gateway to external networks.✅ Layer 2 Exclusive Egress → Each VN has its own dedicated Layer 2 link for external connectivity.

???? Reference: Huawei HCIE Datacom – CloudCampus Fabric Egress Modes

Correct Order for HTTP Request Line:

1. Request Method (e.g., GET, POST)2. URI (Uniform Resource Identifier) (e.g., /index.html)3. Protocol Version (e.g., HTTP/1.1)

Answer:

Request Method

URI

Protocol Version

Comprehensive and Detailed Explanation:

Structure of an HTTP Request Message

An HTTP request message consists of:1️⃣ Request Line → Specifies the request method, the target resource (URI), and the HTTP version.2️⃣ Headers → Provides additional request details (e.g., Host, User-Agent).3️⃣ Body (optional) → Used in methods like POST for sending data.

Format of an HTTP Request Line:

h

CopyEdit

GET /index.html HTTP/1.1

GET → Request method

/index.html → URI (resource being requested)

HTTP/1.1 → Protocol version

Why Other Fields Are Incorrect?

❌ Status Code → This belongs to an HTTP response, not a request.❌ Mixing Headers into the Request Line → Headers should be placed separately after the request line.

Understanding the Network Scenario:

R2 is the boundary router between OSPF and IS-IS.

OSPF and IS-IS do not automatically redistribute routes between each other.

R4's loopback (10.1.4.4/32) exists in the IS-IS domain.

To allow R1 (OSPF) to reach R4’s loopback, R2 must redistribute IS-IS routes into OSPF.

Why Option C Is Correct (✅)

✔ default-route-advertise in OSPF on R2:

This advertises a default route into the OSPF domain, allowing OSPF routers (R1, R3) to forward unknown traffic to R2.

Since IS-IS routes are not automatically injected into OSPF, this ensures R1 can reach R4.

✔ IS-IS Already Has Routes to OSPF

IS-IS routers (R3, R4) already learn routes from OSPF via R2 (assuming route redistribution is properly configured).

No need to run default-route-advertise in IS-IS.

Why Other Options Are Incorrect (❌)

❌ A. Run default-route-advertise in both OSPF and IS-IS views on R2

Unnecessary in IS-IS. The IS-IS domain already learns OSPF routes from R2 via redistribution.

Only OSPF needs a default route to forward unknown traffic to R2.

❌ B. No configuration is required

Incorrect, because OSPF does not automatically learn IS-IS routes.

A default route or redistribution is needed for R1 to reach R4.

❌ D. Run default-route-advertise only in the IS-IS view on R2

Incorrect, because IS-IS already has routing information from OSPF.

The issue is with OSPF not learning IS-IS routes, so the command needs to be in OSPF view.

???? Reference: Huawei HCIE Datacom – OSPF and IS-IS Route Redistribution and Interoperability

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 in Huawei SD-WAN

Huawei SD-WAN uses BGP (Border Gateway Protocol) as the primary routing protocol to exchange VPN routes between Customer Premises Equipment (CPEs) and the controller.

✅ Why BGP is Used in SD-WAN?

Scalability: BGP can handle a large number of VPN routes.

Policy-Based Routing: BGP allows traffic engineering and policy control across SD-WAN tunnels.

Multiprotocol Support: Huawei SD-WAN uses MP-BGP to exchange IPv4, IPv6, and VPNv4 routes.

Understanding the Command Components:

This is a Huawei CLI command used for diagnosing connectivity within a VPN instance in an MPLS network.

ping -aX → Specifies the source IP address (X) of the ping packets.

-cY → Specifies the number of ICMP Echo Request packets to send (Y).

-sZ → Defines the size (in bytes) of each ICMP Echo Request packet (Z).

-vpn-instance M → Specifies the VPN instance (VRF) M to which the ping packets belong.

Why are all options correct?

✅ A. The source IP address of the ping packets is X.

The -aX option forces the ping to originate from IP X instead of the default interface IP.

✅ B. The ping packets belong to VPN instance M.

The -vpn-instance M option ensures the ping is sent within VPN instance M, allowing verification of MPLS L3VPN routing.

✅ C. During the ping operation, the quantity of ICMP Request packets is Y.

The -cY parameter sets the number of ICMP Echo Requests to be sent, making Y the total count.

✅ D. The size of each ICMP Request packet for the ping operation is Z bytes.

The -sZ parameter defines packet size, helping to test MTU (Maximum Transmission Unit) issues.

Real-World Application:

Verifying MPLS VPN connectivity: Ensure customer networks are reachable within separate VRFs.

Testing MTU & fragmentation: Using -sZ, operators can check if packet fragmentation occurs.

Debugging asymmetric routing issues: By forcing -aX, engineers can trace return paths.

✅ Reference: Huawei HCIE-Datacom Official Guide – MPLS VPN Troubleshooting & Ping Options

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

Understanding VXLAN and ARP Suppression in BGP EVPN

VXLAN (Virtual Extensible LAN) is used to extend Layer 2 networks over Layer 3 infrastructure.

VXLAN uses VTEPs (VXLAN Tunnel Endpoints) to encapsulate and forward Layer 2 traffic.

BGP EVPN (Ethernet VPN) is used for MAC/IP address learning and distribution across VXLAN networks.

How ARP Request Forwarding Works in This Scenario?

1️⃣ ARP Broadcast Suppression Enabled (VXLAN Optimized Forwarding)

Since ARP broadcast suppression is enabled on VTEP1, the ARP request is not flooded.

Instead, VTEP1 checks its EVPN learned database to find PC2’s MAC address (MAC C).

2️⃣ VTEP1 Encapsulates the ARP Request

VTEP1 encapsulates the ARP request in a VXLAN packet and sends it to VTEP2.

The original ARP frame inside the VXLAN tunnel still has:

Source MAC: MAC A (PC1's MAC)

Destination MAC: MAC C (PC2's MAC, learned via EVPN)

3️⃣ VXLAN Outer Headers

The outer VXLAN header uses:

Source IP: 1.1.1.1 (VTEP1)

Destination IP: 2.2.2.2 (VTEP2)

VNI (VXLAN Network Identifier): 200 (BD 20)

4️⃣ VTEP2 Receives and Forwards the ARP Request

VTEP2 decapsulates the VXLAN packet and forwards the original ARP request to PC2 (MAC C).

This ensures that only the intended receiver (PC2) gets the ARP request, preventing unnecessary broadcast flooding.

Why the Answer is MAC C?

✅ B. MAC C is Correct

The destination MAC of the inner data frame is PC2’s MAC (MAC C).

This is because VTEP1 forwards the ARP request directly to VTEP2, which then forwards it to PC2.

Why Other Answers Are Incorrect?

❌ A. MAC B (Incorrect)

MAC B is VTEP1’s MAC address, which is used in the outer VXLAN header, not in the inner Ethernet frame.

❌ C. MAC A (Incorrect)

MAC A is the source MAC of the ARP request (PC1), not the destination.

❌ D. MAC D (Incorrect)

MAC D is not mentioned in the topology, so it is irrelevant.

???? Reference: Huawei HCIE Datacom – VXLAN BGP EVPN and ARP Suppression

Understanding SRv6 (Segment Routing over IPv6) Policies

???? What is an SRv6 Policy?

A traffic engineering (TE) mechanism used in SRv6-enabled networks.

Defines a set of Segment Routing (SR) paths that direct packets through a predefined set of waypoints.

Uses SRv6 SIDs (Segment Identifiers) instead of MPLS labels.

???? How Can SRv6 Policies Be Configured?✅ Static SRv6 Policy Configuration:

Manually configured by network administrators.

Used in predictable, fixed network paths.

✅ Dynamic SRv6 Policy Generation:

Created dynamically by an SDN controller (e.g., Huawei iMaster NCE).

The controller analyzes network conditions and adjusts paths automatically based on traffic load and link failures.

Why is the Answer TRUE?

✅ SRv6 policies can be configured manually or dynamically delivered by a controller.✅ SDN-based SRv6 solutions improve network automation and traffic engineering efficiency.

Real-World Application:

Cloud Data Centers: Uses dynamic SRv6 policies for optimal traffic distribution.

5G Transport Networks: Uses SRv6 TE for low-latency service guarantees.

✅ Reference: Huawei HCIE-Datacom Guide – SRv6 Policy and SDN Integration

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

Comprehensive and Detailed Explanation:

Inter-AS MPLS L3VPN Option B requires ASBRs to exchange VPNv4 routes using eBGP with label information.

Analysis of Inter-AS VPN Solutions:

A screenshot of a computer AI-generated content may be incorrect.

Option B uses eBGP to exchange labeled VPNv4 routes between ASBRs but does not require MPLS between ASBRs.

Option A does not exchange VPNv4 routes over ASBRs (uses IP routing instead).

Option C uses MP-BGP and requires full MPLS between ASBRs.

Since Option B requires ASBRs to exchange VPNv4 routes, the correct answer is B.

???? Reference: Huawei HCIE Datacom – MPLS Inter-AS VPNs

Understanding Inter-AS MPLS L3VPN Option C

???? MPLS L3VPN provides Layer 3 VPN services over an MPLS backbone by using BGP to exchange VPN routes.???? Inter-AS MPLS L3VPN Option C (Carrier-to-Carrier Model) works as follows:

ASBRs (Autonomous System Boundary Routers) exchange VPNv4 routes using MP-BGP.

ASBRs do NOT store VPN routing tables. Instead, they advertise labeled IPv4 routes to enable inter-AS forwarding.

How ASBR-PE2 Enables Inter-AS Communication?

✅ VPNv4 Address Family (Answer A - Required)

Used to exchange MPLS VPN routes between PE routers.

MP-BGP (Multiprotocol BGP) exchanges VPNv4 prefixes between ASBR-PE1 and ASBR-PE2.

✅ Unicast BGP Address Family (Answer D - Required)

Required to exchange IPv4 labeled routes between ASBRs.

Ensures MPLS label forwarding between AS100 and AS200.

❌ BGP-LS Address Family (Answer B - Not Required)

BGP-LS (BGP Link-State) is used for SDN controllers to learn topology information.

It is not required for Inter-AS MPLS L3VPN.

❌ VPN Instance Unicast Address Family (Answer C - Not Required)

This is used for PE-CE communication but is not required between ASBRs.

Why is the Answer A, D?

✅ VPNv4 routes enable inter-AS VPN communication.✅ IPv4 unicast routes are required for ASBR-PE2 to forward packets across AS boundaries.

Real-World Application:

Service Provider Networks: Used in carrier-to-carrier MPLS VPN deployments.

Enterprise WAN Interconnection: Enables multi-AS MPLS VPN connectivity for large enterprises.

✅ Reference: Huawei HCIE-Datacom Guide – Inter-AS MPLS L3VPN Option C (Carrier-to-Carrier Model)