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

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

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

In BGP/MPLS IP VPN, when OSPF is used as the PE-CE routing protocol, Domain IDs are used to determine whether the OSPF routes imported into the VPN instance belong to the same OSPF domain.

How Domain ID Works in OSPF and MPLS VPN:

Same Domain ID (OSPF Intra-domain routes)

If the PE router's Domain ID matches the OSPF Domain ID, routes are treated as intra-area routes.

The routes retain OSPF attributes when redistributed into the VPN.

Different Domain ID (OSPF Inter-domain routes)

If the Domain ID does not match, routes are treated as external routes (Type 3 or Type 5 LSAs).

The PE router redistributes these routes as OSPF external routes.

Example Huawei Configuration for Domain ID in OSPF VPN:

ospf 1 vpn-instance VPN1

domain-id 1.1.1.1

This ensures consistent OSPF route types when exchanging routes between PE and CE.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – OSPF Domain ID in PE-CE Routing

HCIE-Datacom Study Material – OSPF & MPLS VPN Route Redistribution

✔ 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

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

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

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

The Differentiated Services (DiffServ) model for Quality of Service (QoS) enables traffic management based on predefined priorities. This involves classifying, policing, queuing, and scheduling traffic to ensure efficient network resource utilization.

Breakdown of Each QoS Processing Step:

✅ Step 1: Traffic Classification and Marking

Purpose: Identifies and marks packets based on QoS attributes such as DSCP (Differentiated Services Code Point) or 802.1p priority bits.

Function: Assigns a QoS label to packets for further processing.

Example: Packets carrying voice traffic (EF - Expedited Forwarding) are marked for high-priority treatment.

✅ Step 2: Traffic Policing (CAR - Committed Access Rate)

Purpose: Enforces bandwidth limits on specific traffic flows to prevent excessive usage.

Function: Drops or re-marks packets exceeding the assigned bandwidth threshold.

Example: If a video stream exceeds 10 Mbps, excess packets may be dropped or re-marked.

✅ Step 3: Congestion Management (Queuing and Scheduling)

Purpose: Manages traffic flow through queues based on assigned QoS levels.

Function: Places packets in appropriate priority queues (e.g., Strict Priority, Weighted Fair Queuing - WFQ, CBWFQ).

Example: Voice packets are assigned to high-priority queues for low-latency forwarding.

✅ Step 4: Congestion Avoidance

Purpose: Prevents network buffer overflows and excessive packet drops.

Function: Uses mechanisms like WRED (Weighted Random Early Detection) to drop lower-priority packets before congestion occurs.

Example: If a queue reaches 80% capacity, WRED may drop low-priority packets to maintain QoS.

✅ Step 5: Traffic Shaping

Purpose: Smooths out traffic bursts to maintain a consistent transmission rate.

Function: Buffers and delays packets to prevent excessive packet drops.

Example: If outgoing traffic exceeds 50 Mbps, shaping ensures it does not exceed this limit while maintaining steady flow.

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

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.