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

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)

A. The device sends sampled data every second → Correct, since sample interval is 1000ms = 1 second.

B. The subscription mode is static subscription → Correct, as shown by Sub state: PASSIVE. Passive indicates a static subscription.

C. The IP address of the device is 192.168.56.1 → Incorrect — this IP address is the destination (telemetry collector), not the device’s own IP.

D. The subscription name is Sub1 → Correct, as per Sub name : Sub1.

Correct answer: C. The IP address of the device is 192.168.56.1 — this is incorrect because it ' s actually the collector’s IP, not the device ' s.

IPsec (Internet Protocol Security) provides secure communication over IP networks through several essential functions. Let’s explain each function and its purpose:

1. Data Origin Authentication:

Description: The receiver verifies the identity of the sender.

Explanation:

This function ensures that the data received actually comes from the claimed source.

IPsec achieves this using IKE (Internet Key Exchange) and digital signatures.

The Authentication Header (AH) and Encapsulating Security Payload (ESP) support authentication.

Use Case: Verifying that a message claiming to be from a specific IP address is genuinely from that source.

2. Data Encryption:

Description: The sender encrypts the data, and the receiver decrypts the data.

Explanation:

Encryption ensures data confidentiality by transforming readable data (plaintext) into unreadable data (ciphertext).

Only the intended receiver with the correct decryption key can convert the ciphertext back to plaintext.

Common encryption algorithms used include AES (Advanced Encryption Standard) and DES (Data Encryption Standard).

Use Case: Protecting sensitive data transferred over public networks.

3. Data Integrity:

Description: The receiver verifies received data to determine whether the data has been tampered with.

Explanation:

Ensures that the data was not altered during transmission.

Uses cryptographic hash functions (e.g., SHA-1, SHA-256) to generate a message digest.

The digest is sent with the data and verified on the receiving side.

Use Case: Detecting any changes made to the data packet during transmission.

4. Anti-Replay:

Description: The receiver rejects duplicate data packets.

Explanation:

Prevents attackers from capturing packets and replaying them later.

Uses sequence numbers to detect replayed or duplicated packets.

The receiver keeps a sliding window of sequence numbers to compare incoming packets.

Use Case: Blocking malicious actors from sending previously intercepted packets to disrupt communication.

Why This Mapping Is Correct:

The functions and descriptions are aligned based on the core concepts of IPsec and the roles they play in ensuring secure data transmission.

Each function addresses a specific aspect of security: authentication, confidentiality, integrity, and replay protection.

On the 2.4 GHz band, only three non-overlapping channels exist: 1, 6, and 11.

In high-density WLAN scenarios, channels like 1, 5, 9, and 13 can be used with lower transmit power to reduce co-channel interference — though they slightly overlap, they can work in dense deployments when managed properly.

On the 5 GHz band, there are many non-overlapping channels. It’s recommended to stagger high and low channels among adjacent APs to avoid interference.

Correct answer: A. TRUE

GRE (Generic Routing Encapsulation) has the following benefits:

B. VPN Construction — GRE is often used to build site-to-site VPNs.

C. ARP Encapsulation — GRE supports Layer 2 protocol encapsulation such as ARP.

D. Multicast Support — GRE tunnels can encapsulate multicast packets, unlike traditional IPsec.

A. Enlarging the hop limit is incorrect — GRE does not inherently change TTL or hop behavior; routing protocols still use standard IP processing.

Exact Extract - Huawei HCIE-Datacom Tunneling Chapter:

“GRE can encapsulate multicast and broadcast packets and supports L2 protocols like ARP. It is often used for VPN construction over the internet.”

DiffServ QoS model operates on per-hop behavior (PHB) and has these limitations:

A. ✅ Single-hop behavior; no end-to-end path awareness.

B. ✅ Cannot guarantee dedicated resources to individual users.

C. ✅ Does not address traffic bursts; congestion is still possible.

D. ✅ Queue limitations hinder fine-grained SLA assurance and deterministic delay.

Exact Extract – HCIE-Datacom QoS Section:

“DiffServ provides PHB without path-level control. It cannot guarantee SLA for individual users due to limited queuing mechanisms and lack of end-to-end visibility.”

Comprehensive and Detailed In-Depth Explanation:

The Huawei SD-WAN Solution uses HTTP/2 as the primary protocol to report device performance data to the controller.

HTTP/2 is chosen for its high efficiency, low latency, and enhanced data transfer speed.

It supports bidirectional communication between devices and the iMaster NCE-Campus controller.

While protocols like NetFlow and SNMP are traditionally used for monitoring, Huawei SD-WAN specifically uses HTTP/2 for real-time performance reporting and control due to its modern web-based architecture.

Ethernet Segment Identifier (ESI) is a 10-byte identifier used in EVPN (Ethernet VPN) to uniquely identify an Ethernet segment across a network, particularly in multi-homing scenarios. It ensures loop prevention and redundancy.

Exact Extract - HCIE-Datacom EVPN Section:

“The ESI is a 10-byte identifier and must be unique across the entire EVPN network. It plays a key role in identifying Ethernet segments in multi-homed environments.”

Comprehensive and Detailed In-Depth Explanation:

When IS-IS is used as the IGP (Interior Gateway Protocol) to advertise Segment Routing (SR) SIDs, the Level-2 (L2) router advertises node SIDs globally across the entire IS-IS domain, not just within a single area.

Level-1 (L1) routers only advertise within the local area, but L2 routers distribute information across multiple areas, enabling inter-area reachability.

Therefore, the statement is FALSE.

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