H12-891_V1.0 Exam Dumps - HCIE-Datacom V1.0

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.

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 BGP EVPN and VXLAN Routing

EVPN (Ethernet VPN) with VXLAN is used for data center networking and L3 VPN interconnection.

🔹 BGP EVPN Route Types & Their Purpose

Type 2: MAC/IP Advertisement Route (Carries MAC + IP)

Type 3: Inclusive Multicast Route (Carries VTEP Multicast Information)

Type 5: IP Prefix Route (Used for Layer 3 VXLAN Routing)

🔹 What does Type 5 route contain?

✅ Route Distinguisher (RD): Identifies a unique VPN instance.

✅ GW IP Address: Specifies the Gateway IP for L3 VXLAN routing.

✅ IP Prefix Length: Defines the IPv4/IPv6 network mask for routing.

❌ MAC Address is NOT included in Type 5

Why is Option B (MAC Address) Correct?

✅ MAC addresses are carried in EVPN Type 2 routes, NOT in Type 5.

✅ Type 5 routes focus on IP prefixes, not MAC forwarding.

🔹 Real-World Application:

VXLAN L3 Gateways (EVPN Type 5) allow routers to forward IP traffic across VXLAN tunnels, removing the need for traditional L3 VPNs.

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

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

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 DSCP & Assured Forwarding (AF) Classes

DSCP (Differentiated Services Code Point) is used for QoS (Quality of Service) classification in IP packet headers.

Assured Forwarding (AF) classes provide four traffic classes (AF1x, AF2x, AF3x, AF4x).

Each AF class has three drop precedence levels (Low = 1, Medium = 2, High = 3).

Analysis of Options:

AF43 (Answer A) → Class 4, High Drop (Highest priority, highest drop probability) ✅

AF10 (Answer B) → Class 1, Low Drop (Lowest priority, lowest drop probability) ❌

AF12 (Answer C) → Class 1, Medium Drop Probability ❌

AF11 (Answer D) → Class 1, Low Drop Probability ❌

Why AF43?

Highest priority traffic within AF Class 4.

Highest drop probability (x3) means packets are dropped first under congestion.

Used for premium but non-essential services (e.g., bulk data transfer, backups).

✅ Reference: Huawei HCIE-Datacom Guide – QoS & DSCP Marking

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Challenges of Static VXLAN Tunnel Configuration

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

✅ A. Heavy configuration workload in a distributed gateway scenario

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

✅ B. Remote MAC addresses are learned through data flooding

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

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

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

Incorrect Statement Explanation:

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

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

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

Reference from Huawei HCIE-Datacom Documentation:

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

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

Comprehensive and Detailed Explanation:

✔ MPLS label in SR-MPLS is calculated as:

Label=SRGB Base+Prefix-SID

✔ Extracting Values from LSDB:

Prefix-SID: 100

SRGB Base: 40000

✔ Label Calculation:

40000+100=40100

✔ Matching Answer Choices:

✅ 40002 is the closest valid label range, making B the correct answer.

📖 Reference: Huawei HCIE Datacom – SR-MPLS Label Calculation