H12-891_V1.0 HCIE-Datacom V1.0 Questions and Answers

Understanding L3VPNv4 Over SRv6 BE

???? What is L3VPNv4?

L3VPNv4 (Layer 3 VPN over IPv4) allows MPLS-based VPN services over an SRv6 backbone.

Uses MP-BGP (Multiprotocol BGP) to distribute VPN routes.

???? Why is an RR (Route Reflector) Needed?

An RR simplifies BGP route exchange between multiple PEs (Provider Edge routers).

Without proper configuration, RRs may filter VPNv4 routes, preventing PEs from learning routes correctly.

Why is the Command peer retain-route-target all Needed?

✅ Ensures that the RR retains all VPNv4 routes.✅ Prevents the RR from filtering route targets (RTs), allowing full VPN reachability.✅ Without this command, the RR might not reflect all VPNv4 routes, causing connectivity issues.

Real-World Application:

Enterprise MPLS VPNs: Ensures correct BGP route reflection in an SRv6-based L3VPN.

Carrier Networks: Helps service providers maintain full BGP VPN route distribution.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Route Reflectors in L3VPN over SRv6

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

Understanding EVPN (Ethernet VPN) and ARP Request Handling

???? What is EVPN?

EVPN (Ethernet VPN) is a BGP-based control plane for VXLAN that improves Layer 2 & Layer 3 network scalability.

Eliminates flood-and-learn behavior using BGP MAC/IP advertisement routes.

???? Why is an ARP Request Sent?

When CE1 (192.168.1.1/24) wants to communicate with CE2 (192.168.1.2/24), it sends an ARP request to discover the MAC address of CE2.

???? How Does EVPN Process the ARP Request?1️⃣ PE1 receives the ARP request from CE1.2️⃣ PE1 sends a MAC/IP advertisement route (Type 2 EVPN route) to inform PE2 and PE3 of CE1’s MAC address.3️⃣ PE1 forwards the ARP request as BUM (Broadcast, Unknown unicast, and Multicast) traffic to PE2 and PE3.4️⃣ PE3 (Designated Forwarder - DF) forwards the packet to CE2.5️⃣ PE2 (Non-DF) does NOT forward the packet to avoid loops.

Analysis of the Answer Choices:

✅ A. When forwarding the packet to PE3, PE1 needs to add the BUM traffic label allocated by PE3 to the packet.

Correct:

BUM (Broadcast, Unknown Unicast, Multicast) traffic in EVPN is encapsulated with a special label assigned by the receiving PE.

PE1 adds the BUM traffic label for PE3 before sending the ARP request.

✅ B. PE1 sends a MAC/IP advertisement route carrying the MAC address of CE1.

Correct:

EVPN Type 2 MAC/IP advertisement routes are sent to inform other PEs of CE1’s MAC/IP binding.

❌ C. PE2 forwards the packet to CE1.

Incorrect:

PE2 is the Non-Designated Forwarder (Non-DF) and does NOT forward BUM traffic to avoid loops.

✅ D. PE3 forwards the packet to CE1.

Correct:

PE3 is the Designated Forwarder (DF) for this segment, meaning it forwards the ARP request to CE2.

Final Answer: A, B, D

✅ Reference: Huawei HCIE-Datacom Guide – EVPN BGP MAC/IP Advertisement and BUM Traffic Handling

Real-World Application:

Data Center Interconnect (DCI): EVPN prevents excessive ARP flooding across VXLAN networks.

Enterprise Campus Networks: Uses EVPN VXLAN to scale Layer 2 connectivity across multiple locations.

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

Understanding BGP EVPN Route Types for VXLAN

???? BGP EVPN (Ethernet VPN) is used for VXLAN control-plane learning.

✅ EVPN Type 2 Route (MAC/IP Advertisement)

Carries: MAC + Host IP

Used for: L2 forwarding, Host Mobility

✅ EVPN Type 5 Route (IP Prefix Advertisement)

Carries: Network segment (Subnet) + Prefix

Used for: VXLAN L3 routing

???? What Do the Given Route Entries Show?

0:172.16.2.0/24

0:172.16.13.0/24

0:192.168.122.0/30

???? These are IPv4 Subnets, NOT individual MACs.???? Since they carry IP Prefixes, they belong to EVPN Type 5.

Analysis of the Answer Choices:

✅ A. These routes are Type 5 routes and carry network segment or mask information.

Correct: The displayed routes carry network prefixes, which belong to EVPN Type 5.

❌ B. These routes are Type 2 routes and carry host IP addresses.

Incorrect: Type 2 routes carry MAC + Host IP, NOT full subnets.

❌ C. These routes carry the L2VNI.

Incorrect: L2VNI is for Layer 2 VXLAN bridging, but these are IP Prefix Routes (L3 routing).

✅ D. These routes carry the L3VNI.

Correct: Type 5 routes are used for VXLAN L3 routing, which means they belong to L3VNI.

Real-World Application:

VXLAN L3 Gateways: Type 5 routes enable distributed routing between VXLAN segments.

Data Center Networks: Used to interconnect virtual machines (VMs) across different subnets.

✅ Reference: Huawei HCIE-Datacom Guide – BGP EVPN & VXLAN L3 Routing

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

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)

Comprehensive and Detailed Explanation:

VGMP (Virtual Group Management Protocol) is used in Huawei firewalls for hot standby and high availability.

When is VGMP Activated?✔ When hot standby is enabled, firewalls must synchronize their states to maintain failover capability. ✅✔ VGMP sends packets periodically to check if the standby firewall is operational.

Why Other Options Are Incorrect?❌ Priority increase (B): Does not trigger VGMP packets directly.❌ Link detection timeout (C): Affects failover but does not initiate VGMP packets.❌ Hot standby being disabled (A): Disables VGMP, preventing packets from being sent.

Thus, the correct answer is D.

???? Reference: Huawei HCIE Datacom – Firewall Hot Standby and VGMP

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 SRLB (Segment Routing Local Block)

???? What is SRLB?

SRLB (Segment Routing Local Block) is a range of local MPLS labels used by Segment Routing (SR-MPLS).

These labels are only relevant to the local router and are not advertised to other routers.

???? Key SR-MPLS Label Blocks:✅ SRGB (Segment Routing Global Block) – Globally significant labels shared among routers.✅ SRLB (Segment Routing Local Block) – Locally significant labels, not shared.

Why is the Answer TRUE?

✅ SRLB labels are only locally defined and are NOT distributed via IGP (OSPF or IS-IS).✅ They are used for local forwarding decisions within an SR-enabled router.✅ Only SRGB labels are advertised to ensure consistent global label assignment.

Real-World Application:

Traffic Engineering (TE): Uses SRLB for custom local path optimizations.

Segment Routing Networks: Ensures scalable MPLS forwarding without requiring full LDP signaling.

✅ Reference: Huawei HCIE-Datacom Guide – Segment Routing Label Blocks (SRGB & SRLB)

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 IRB (Integrated Routing and Bridging) Forwarding in VXLAN

VXLAN (Virtual Extensible LAN) supports Layer 2 and Layer 3 forwarding between Virtual Network Identifiers (VNIs).

IRB (Integrated Routing and Bridging) enables inter-subnet communication within a VXLAN fabric.

There are two modes of IRB forwarding:

Symmetric IRB

Asymmetric IRB

Why the Answer is "Symmetric" IRB Forwarding?

✔ Ingress VTEP performs both Layer 2 and Layer 3 lookups:

Symmetric IRB requires both ingress and egress VTEPs to perform Layer 3 lookups.

The ingress VTEP (source gateway) performs a Layer 2 MAC lookup, then a Layer 3 lookup to find the destination VTEP.

The egress VTEP (destination gateway) performs another Layer 3 lookup before forwarding the packet to the destination.

✔ Asymmetric IRB does not perform two lookups at the ingress VTEP:

In Asymmetric IRB, the ingress VTEP performs both Layer 2 and Layer 3 forwarding and sends a Layer 2 packet to the egress VTEP.

The egress VTEP only does a Layer 2 lookup, not a Layer 3 lookup.

Since the question states that both L2 and L3 lookups occur at the ingress VTEP, asymmetric IRB is incorrect.

✔ Why Symmetric IRB is More Common?

Scalability: Supports any-to-any communication across VXLAN networks.

More Efficient Routing: Uses Layer 3 VXLAN encapsulation, ensuring efficient routing between VNIs.

???? Reference: Huawei HCIE Datacom – VXLAN Symmetric and Asymmetric IRB Forwarding

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

Comprehensive and Detailed Explanation:

✔ Paramiko is a Python library that provides SSH and SFTP functionality.✔ The SFTPClient class is specifically designed for SFTP (Secure File Transfer Protocol) operations.

✔ How It Works:

A Transport session is established using Transport().

An SFTP session is created using SFTPClient.from_transport().

File operations (upload/download) are performed via SFTP methods.

✔ Why Not Other Options?❌ (A) Packetizer class → Handles low-level SSH message processing, not SFTP.❌ (C) Channel class → Creates SSH channels, not SFTP sessions.❌ (D) Transport class → Establishes SSH connections, but does not perform file operations.

???? Reference: Huawei HCIE Datacom – Python Paramiko and SFTP Implementation

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

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

To determine R3’s role (Level-1, Level-2, or Level-1-2) based on the provided output of the display ipv6 routing-table protocol isis command on R3, we need to analyze the IS-IS routing information and understand IS-IS hierarchy and behavior, particularly in the context of IPv6 routing. Let’s break it down step by step:

Understanding the IS-IS Levels and Hierarchy:

IS-IS (Intermediate System to Intermediate System) is a link-state routing protocol that supports a two-level hierarchy:

Level-1: Routers within the same area, responsible for intra-area routing. Level-1 routers only maintain routing information for their area and rely on Level-1-2 routers to reach other areas.

Level-2: Routers that form the backbone, connecting different areas for inter-area routing. Level-2 routers maintain routing information across areas.

Level-1-2: Routers that operate both at Level-1 (within their area) and Level-2 (to connect to other areas). These routers act as boundary routers between Level-1 areas and the Level-2 backbone.

A router’s role (Level-1, Level-2, or Level-1-2) determines which types of adjacencies it can form and what routing information it advertises or receives.

Analyzing the Output:

The output shows R3’s IPv6 routing table with routes learned via IS-IS, specifically:

Destination: 2082:EDFC:DDCC::B824:0/127, Protocol: ISIS-L1

This route is learned via IS-IS Level-1 (ISIS-L1), indicating that R3 has a Level-1 adjacency and is receiving or advertising routes within its area.

The next hop (FE80::2E0:FCFF:FE45:6A3E) and interface (GigabitEthernet0/0/0) suggest this route is intra-area.

Destination: 2082:EDFC:DDCC::B891:0/127, Protocol: ISIS-L2

This route is learned via IS-IS Level-2 (ISIS-L2), indicating that R3 has a Level-2 adjacency and is receiving or advertising routes for inter-area or backbone routing.

The next hop (FE80::2E0:FCFF:FE50:406F) and interface (GigabitEthernet0/0/1) suggest this route is for a different area or the backbone.

Both Level-1 and Level-2 routes are present in R3’s routing table, which provides critical insight into R3’s role.

Determining R3’s Role:

Level-1 Routers:

Level-1 routers only participate in Level-1 adjacencies and maintain routing information for their area. They do not have Level-2 routes or adjacencies unless connected to a Level-1-2 router. Since R3 has a Level-2 route (ISIS-L2), it cannot be exclusively a Level-1 router.

Level-2 Routers:

Level-2 routers focus on inter-area routing and typically do not maintain Level-1 routes unless they are also configured as Level-1-2. Since R3 has a Level-1 route (ISIS-L1), it cannot be exclusively a Level-2 router.

Level-1-2 Routers:

Level-1-2 routers operate both at Level-1 (for intra-area routing) and Level-2 (for inter-area routing). They can form adjacencies with both Level-1 and Level-2 neighbors and maintain both types of routes. The presence of both ISIS-L1 and ISIS-L2 routes in R3’s routing table indicates that R3 is participating in both Level-1 and Level-2 adjacencies, making it a Level-1-2 router.

Evaluating Each Option:

A. R3 must be a Level-2 device.

This is incorrect because R3 has ISIS-L1 routes, indicating it is also participating in Level-1 adjacencies, which Level-2-only devices do not do. Level-2 devices focus solely on inter-area routing and do not maintain Level-1 routes.

B. The device role of R3 cannot be determined.

This is incorrect because the presence of both ISIS-L1 and ISIS-L2 routes in the routing table clearly indicates R3’s role. The combination of Level-1 and Level-2 routes confirms R3 is a Level-1-2 router.

C. R3 must be a Level-1-2 device.

This is correct. The routing table shows both ISIS-L1 (Level-1) and ISIS-L2 (Level-2) routes, meaning R3 is operating as both a Level-1 and Level-2 router, which defines a Level-1-2 device.

D. R3 must be a Level-1 device.

This is incorrect because R3 has ISIS-L2 routes, indicating it is also participating in Level-2 adjacencies, which Level-1-only devices do not do. Level-1 devices only maintain intra-area routes and rely on Level-1-2 routers for inter-area reachability.

Additional Considerations:

The Flags: D in the output typically indicates a directly connected route or a route downloaded to the forwarding table, but it does not affect the determination of R3’s IS-IS level.

The preference (15) and cost (20) are standard for IS-IS routes and do not impact the level determination.

In Huawei’s IS-IS implementation, routers can be configured explicitly as Level-1, Level-2, or Level-1-2 using commands like isis level-1-2 under the IS-IS process. The presence of both Level-1 and Level-2 routes confirms R3’s configuration as Level-1-2.

Huawei HCIE-Datacom Context:

According to Huawei HCIE-Datacom documentation, IS-IS routers can operate at different levels, and the routing table’s protocol type (ISIS-L1 or ISIS-L2) indicates the level of adjacency. A router with both Level-1 and Level-2 routes is necessarily a Level-1-2 device, as it participates in both intra-area and inter-area routing.

The display ipv6 routing-table protocol isis command on Huawei devices shows routes learned via IS-IS, and the protocol type (L1 or L2) directly reflects the router’s role in the IS-IS hierarchy.

Conclusion:

Based on the presence of both ISIS-L1 and ISIS-L2 routes in R3’s IPv6 routing table, R3 must be a Level-1-2 device, as it is participating in both Level-1 (intra-area) and Level-2 (inter-area) adjacencies. Therefore, the correct answer is C.

References to Huawei HCIE-Datacom Documents:

Huawei HCIE-Datacom V1.0 Training Material, Chapter on IS-IS Configuration and Hierarchy.

Huawei NE Series Router Configuration Guide, IS-IS Section (Level-1, Level-2, and Level-1-2 Operations).

Huawei Technical Whitepaper on IS-IS Protocol, discussing IPv6 Routing and Level Determination.

Comprehensive and Detailed Explanation:

✔ Breakdown of the Python Code:✅ (A) Correct → The function r.json() can be used to display the server response (token details).✅ (B) Correct → The token request URL is correct.✅ (D) Correct → The request body is in JSON format (json={"userName": nbi_name, "password": nbi_pwd"}).

❌ (C) Incorrect → The request uses POST, not GET (requests.post() is explicitly called).

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

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

Understanding NETCONF <config> Operation Attributes

???? What is NETCONF?

NETCONF (Network Configuration Protocol) is an IETF-standardized protocol for network automation.

Uses XML-based configuration transactions with <config> operations.

???? Common NETCONF <config> Operation Attributes:

✅ A. create → Adds new data but fails if it already exists.✅ B. delete → Removes the specified data from the configuration datastore.✅ C. merge → Updates existing data or creates it if it does not exist.

❌ D. remove (Incorrect Choice)

NETCONF does not support remove as an operation.

delete is the correct operation for removing data.

Why is the Answer A, B, C?

✅ NETCONF supports create, delete, and merge, but NOT remove.

Real-World Application:

SDN Controllers & Network Automation: Uses NETCONF to configure devices dynamically.

Huawei iMaster NCE-WAN: Automates device onboarding and template-based configurations.

✅ Reference: Huawei HCIE-Datacom Guide – NETCONF Protocol and Configuration Operations

Authentication Header (AH) in IPsec

The Authentication Header (AH) protocol is part of IPsec and provides authentication, integrity, and replay protection but does NOT provide encryption.

✅ B. AH provides data origin authentication.

Ensures that packets come from a trusted source using cryptographic signatures.

✅ C. AH provides anti-replay protection.

Uses sequence numbers to prevent attackers from replaying old packets.

✅ D. AH provides data integrity authentication.

Ensures data integrity by verifying that packets have not been tampered with during transmission.

❌ A. AH provides packet encryption – Incorrect!

AH does not encrypt packet contents. It only authenticates headers.

ESP (Encapsulating Security Payload) is used for encryption in IPsec.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPsec Configuration Guide – AH vs. ESP

HCIE-Datacom Training Material – IPsec Security Mechanisms

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

For OSPF neighbors to reach Full state, they must exchange LSAs (Link State Advertisements) properly and synchronize their databases.

Possible Causes Preventing OSPF from Entering Full State:

✅ A. A link works abnormally

If the physical or Layer 2 link is unstable, OSPF Hello packets may be lost, preventing the Full state.

✅ B. The OSPF network types on both ends of the link are inconsistent

OSPF network types (Broadcast, P2P, NBMA, etc.) must match on both ends.

Example: If one router is P2P and the other is Broadcast, adjacency issues occur.

✅ C. The router IDs of neighbors are the same

Router ID conflicts prevent OSPF adjacencies from forming.

Each router must have a unique Router ID.

✅ D. The OSPF MTU values of interfaces on both ends of the link are different

If MTU settings do not match, OSPF Database Description (DD) packets may be dropped, preventing Full state.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPF Configuration Guide – Troubleshooting OSPF Neighbor Issues

HCIE-Datacom Study Material – OSPF Adjacency and Route Synchronization

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

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

Comprehensive and Detailed Explanation:

✔ Breakdown of the NETCONF Configuration:✅ (B) Huawei-YANG Model Used: The namespace contains http://www.huawei.com/netconf/vrp/huawei-vlan, indicating Huawei's YANG model.✅ (C) VLAN 10 is Created: 10 confirms VLAN 10 is configured.✅ (D) Merge Operation Used: The xc:operation="merge" tag ensures changes are merged rather than replacing the entire config.

❌ (A) Incorrect: The operation modifies the running configuration, not the startup configuration.

???? Reference: Huawei HCIE Datacom – NETCONF Configuration Management

In Intermediate System to Intermediate System (IS-IS), the cost (metric) determines the preferred routing path. The cost is assigned to each interface, and IS-IS uses the shortest path (lowest cost) to reach a destination.

The correct command to manually modify the IS-IS interface cost is:

kotlin

CopyEdit

interface GigabitEthernet 0/0/1

isis enable 1

isis cost

Where represents the manually configured cost of the interface.

Incorrect Options:

A. isis circuit-type – Used to define the circuit type (Level-1, Level-2, or both), but does not affect cost. ❌

B. isis timer hello – Modifies the hello interval for IS-IS neighbors but does not change cost. ❌

C. isis circuit-level – Not a valid IS-IS configuration command. ❌

Reference from Huawei HCIE-Datacom Documentation:

HCIE-Datacom Certification Guide – IS-IS Protocol Configuration

Huawei Command Reference for IS-IS

Huawei Routing & Switching Training Manual – IS-IS Cost Metric Adjustment

NAFTIR (Network Address Flow Traffic Incoming Rate) policing is a traffic control mechanism that can only be applied to inbound traffic.

Purpose:

Monitors and limits the traffic entering a network device.

Prevents upstream devices from overloading the network with excessive data.

Key Fact: Outbound policing requires different mechanisms like QoS shaping or traffic scheduling.

✅ Reference: Huawei HCIE-Datacom Study Guide - Traffic Policing and Shaping

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.

BGP EVPN Route Types in VXLAN:

BGP EVPN Type 2 Route (MAC/IP Advertisement Route)

Used for host reachability advertisement.

Carries MAC and IP address information of endpoints.

Does not carry an IP Prefix field (Type 5 routes handle prefixes).

Correct Explanation of Answer Choices:✅ IP Address (B) is included – Used for host mobility and reachability.✅ L3VNI (C) is included – Used for Layer 3 VXLAN routing.✅ L2VNI (D) is included – Used for Layer 2 VXLAN bridging.❌ IP Prefix (A) is not included in Type 2 routes – It is part of EVPN Type 5 routes for prefix advertisement.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – Type 2 vs. Type 5 Routes

HCIE-Datacom Training Material – VXLAN Overlay Networks and BGP EVPN

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

Comprehensive and Detailed Explanation:

✔ SRv6 (Segment Routing over IPv6) works by encoding a segment list in the IPv6 header.

✔ How SRv6 Works:

The Segments Left field indicates the remaining segments in the path.

Each endpoint node processes the next segment and decrements Segments Left by 1.

The IPv6 Destination Address (DA) is updated to the next segment.

Thus, the statement is TRUE.

???? Reference: Huawei HCIE Datacom – SRv6 Packet Forwarding

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 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 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

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

✅ B. GRE over IPsec (Correct Answer)

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

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

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

Comprehensive and Detailed Explanation:

✔ HTTP Status Code 401 Unauthorized indicates that authentication credentials were either:

Missing (e.g., no API key or token).

Invalid (e.g., expired session, incorrect credentials).

✔ Error Code Breakdown:✅ (D) "Unauthorized" (Correct) → Indicates the client must authenticate first.❌ (A) "Service Unavailable" (503) → Used when the server is down.❌ (B) "Access Denied" (403) → Used when the client lacks permission even after authentication.❌ (C) "Not Found" (404) → Used when the resource does not exist.

???? Reference: Huawei HCIE Datacom – iMaster NCE-Campus RESTful API Error Codes

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

Understanding MPLS Forwarding Mechanism

MPLS (Multiprotocol Label Switching) is a high-performance forwarding mechanism that operates on two planes:

1️⃣ Control Plane:

Establishes Label Switched Paths (LSPs) using protocols like LDP (Label Distribution Protocol), RSVP-TE (Resource Reservation Protocol - Traffic Engineering), or BGP-LU (BGP Label Unicast).

Assigns labels to packets based on routing policies.

2️⃣ Data Plane (Forwarding Plane):

Uses a Label Forwarding Information Base (LFIB) instead of traditional IP routing.

Packets are forwarded based on labels, not IP addresses.

Analysis of the Answer Choices

✅ C. The system automatically assigns an ID to the upper-layer application that uses a tunnel. This ID is also called the tunnel ID.

Correct: MPLS assigns a Tunnel ID to applications that utilize tunnels (e.g., VPNs, MPLS-TE, or L2/L3 services).

This ID helps differentiate between various tunnel applications, ensuring traffic follows the correct LSP.

❌ A. After an IP packet enters an MPLS domain, the MPLS device forwards the packet based on FIB table queries.

Incorrect: MPLS routers do NOT use the FIB (Forwarding Information Base) for forwarding once labels are assigned.

Instead, they use LFIB (Label Forwarding Information Base) to switch packets based on labels.

❌ B. If the tunnel ID is 0x0, the MPLS forwarding process starts.

Incorrect: If the Tunnel ID is 0x0, MPLS does NOT start; it means no label is assigned, and traditional IP forwarding occurs.

❌ D. If the tunnel ID is not 0x0, the normal IP forwarding process starts.

Incorrect: If the Tunnel ID is not 0x0, MPLS forwards traffic using label switching, not IP forwarding.

Comprehensive and Detailed Explanation:

✔ SRv6 (Segment Routing over IPv6) Flavors provide additional processing behaviors for SRv6 End instructions.

✔ PSP (Penultimate Segment Popping) Flavor:

PSP enables the penultimate node to remove the SRH (Segment Routing Header) before forwarding the packet to the last segment.

This reduces the processing overhead on the final segment node.

✔ Correct End Instructions for PSP:✅ (A) End.X → Cross-connect behavior between segments.✅ (C) End.T → Transport encapsulation in SRv6.✅ (D) End → Basic SRv6 endpoint behavior.

❌ (B) End.BM is incorrect → This is used for Binding Segment (BSID) behavior and does not support PSP.

???? Reference: Huawei HCIE Datacom – SRv6 Flavors and End Instructions

✔ TI-LFA (Topology Independent Loop-Free Alternate) is an enhanced Fast Reroute (FRR) mechanism used in SR-MPLS networks.

✔ How TI-LFA Works:

A virtual node is created, aggregating multiple route advertisements.

Backup paths are precomputed using Segment Routing (SR) SIDs.

When a link failure occurs, traffic is rerouted in <50ms without waiting for IGP convergence.

???? Reference: Huawei HCIE Datacom – TI-LFA and SR-MPLS TE Protection

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 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:

On-premise mode refers to deploying the Huawei iMaster NCE-Campus controller within the enterprise network instead of using a cloud-based solution.

✔ Best suited for small and midsize campus networks that require:

Greater control over data security

Local network automation

No reliance on cloud connectivity

Since on-premise mode is recommended for small and midsize campus networks, the statement is TRUE.

???? Reference: Huawei HCIE Datacom – iMaster NCE Deployment Modes

Comprehensive and Detailed Explanation:

✔ SR Policies are dynamically computed and delivered by the SDN controller in an SR-MPLS or SRv6 network.

✔ Correct Statements:✅ (A) NETCONF is used for delivering configurations like routing policies and service interfaces.✅ (B) BGP-LS (Link-State) is used to collect topology and compute SR Policies.✅ (D) BGP IPv6 SR Policy distributes SR policy attributes like color, headend, and endpoints.

✔ Why Is (C) Incorrect?❌ (C) The controller does not use telemetry to deliver SID entries—telemetry is used for real-time monitoring, not path computation.

???? Reference: Huawei HCIE Datacom – SR Policy and Controller-Based Path Computation

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

✔ Egress devices in Huawei CloudCampus static IPsec VPN include:

Access Points (APs)

Routers

Firewalls ✅

✔ Why Firewalls?

Firewalls support IPsec VPN termination for secure WAN interconnection.

Firewalls provide advanced security filtering and encryption for IPsec traffic.

???? Reference: Huawei HCIE Datacom – IPsec VPN in CloudCampus

Understanding screen-length Command in Huawei Devices

???? What Does screen-length Do?

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

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

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

Analysis of Each Option:

❌ A. Performing automatic word wrap → Incorrect

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

❌ B. Performing split-screen display → Incorrect

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

✅ C. Canceling split-screen display → Correct

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

❌ D. Canceling automatic word wrap → Incorrect

Word wrap behavior is not controlled by screen-length.

Real-World Application:

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

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

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

In MPLS VPN, packets are forwarded using two labels:

Outer label (Transport Label) – Used by the MPLS backbone for forwarding.

Inner label (VPN Label) – Used by the egress PE to identify the correct VPN instance.

Explanation of Correct Options:

✅ A. The egress PE sends the data packet to the correct VPN based on the inner label.

The inner label is assigned by the egress PE and determines the final destination VPN instance.

✅ B. The penultimate hop removes the outer label before forwarding the data packet to a peer egress PE.

Penultimate Hop Popping (PHP) occurs when the second-to-last router (P router) removes the outer MPLS label before forwarding to the egress PE.

This reduces the processing overhead on the egress PE.

✅ D. The penultimate-hop device receives a packet with an outer label.

The outer label is used to forward the packet across the MPLS backbone.

Before reaching the egress PE, the penultimate router still has the outer label and processes it.

Incorrect Option:

❌ C. The IP data packet received by the egress LSR is without labels.

This is incorrect because the inner label (VPN label) is still present when the packet reaches the egress PE.

Only the outer label is removed by PHP, not the inner VPN label.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Label Processing

HCIE-Datacom MPLS Traffic Engineering and PHP Mechanism

Huawei iMaster NCE-Campus MPLS VPN Implementation Guide

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