H12-891_V1.0 Exam Dumps - Huawei HCIE-Datacom Questions and Answers

Comprehensive and Detailed Explanation:

The IS-IS peer output shows:

IPv4 Peer Address: 10.1.34.1

IPv6 Peer Address: FE80::2E0:FCFF:FE98:2576

MT IDs (Multi-Topology) Supported: 0 (IPv4), 2 (IPv6)

Since both IPv4 and IPv6 peer addresses are listed, it confirms that both IPv4 and IPv6 IS-IS neighbor relationships are established between R4 and ee8c.a0c2.baf3.

???? Reference: Huawei HCIE Datacom – IS-IS Multi-Topology Support

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

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.

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

Mismatched Area Addr(L1): 13

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

Why is Option D Correct?

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

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

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

Why Are the Other Options Incorrect?

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

Thus, the correct answer is D.

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

Understanding SR-MPLS Prefix and Adjacency Segments

???? What Are Prefix Segments?

Globally unique labels assigned to network prefixes.

Advertised via IGP (OSPF, IS-IS) with SRGB (Segment Routing Global Block).

???? What Are Adjacency Segments?

Locally significant labels assigned to direct router adjacencies.

Not globally visible—only used within a local router’s LFIB (Label Forwarding Information Base).

Why is the Answer FALSE?

❌ Prefix Segments are globally unique, but Adjacency Segments are only locally significant.❌ Adjacency Segments are not distributed globally through IGP.✅ Only Prefix Segments use globally advertised SRGB labels.

Real-World Application:

Segment Routing Traffic Engineering (SR-TE): Uses prefix segments for global routing and adjacency segments for local path steering.

5G Core Networks: Uses SR-MPLS with Prefix SIDs for scalable path selection.

✅ Reference: Huawei HCIE-Datacom Guide – SR-MPLS Prefix & Adjacency Segments

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:

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

Comparison Between Paramiko (SSH) and Telnetlib (Telnet)

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

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

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

✅ Why is Telnet Insecure?

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

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

Correct Method for Secure Remote Login in Python:

Use Paramiko for SSH-based secure automation.

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

import paramiko

ssh = paramiko.SSHClient()

ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

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

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

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

ssh.close()

Reference from Huawei HCIE-Datacom Documentation:

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

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

Understanding Performance Measurement in Huawei CloudWAN

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

???? Traditional Performance Monitoring Methods

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

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

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

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

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

Packet forwarding behavior at each hop without injecting synthetic traffic.

Path delay and service degradation detection.

Why is Answer D Correct?

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

Real-World Application:

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

CloudWAN Optimization: Detects network congestion without affecting user traffic.

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

Comprehensive and Detailed Explanation:

✔ SRv6 Locator and Segment Structure:

The SRv6 Locator is 2001:DB8:ABCD::/64 → This defines the segment routing namespace for this node. ✅

Dynamic Segment (SID) = 32 bits → Defined dynamically per segment. ✅

Args Field = 32 bits → Used for function arguments. ✅

❌ (B) Incorrect → Static segments are NOT explicitly defined as 32-bit fields in Huawei SRv6.

???? Reference: Huawei HCIE Datacom – SRv6 Locator and SID Structure