Pass the Huawei HCIE-Datacom H12-891_V1.0 Questions and answers with CertsForce

From the output:

Tunnel destination IP address: Clearly shown as destination 10.0.1.1 →✅

Tunnel interface MTU: Shown as The Maximum Transmit Unit is 1500 →✅

Tunnel interface IP: Shown as Internet Address is 20.1.1.2/24 →✅

Tunnel source: Tunnel source 10.0.3.3 (LoopBack0) → Not 10.0.1.1 →❌

Therefore:

A— Correct

B— Correct

C— Correct

D— Incorrect (confuses destination as source)

Correct answers: A, B, C

Understanding MPLS Label Retention Modes

In MPLS (Multiprotocol Label Switching), aLabel Switching Router (LSR)can operate in one of two label retention modes:

1️⃣Liberal Label Retention Mode (LLRM)

Stores all labels receivedfrom neighbors, even if they are not immediately used.

Advantage:Fast convergenceduring link failures.

Disadvantage:Consumes more memory & label space.

2️⃣Conservative 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:InLiberal Mode, the routeraccepts and stores all labelsreceived, even for non-best paths.

✅D. The liberal mode requires more memory and label space.

Correct:Since the routerkeeps all labels, it requireshigher 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 describesConservative 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

HTTP/2 is a TCP-based protocol, not UDP-based. It runs on top of TCP port 443 (usually via TLS). The protocol enhances performance using multiplexing, header compression, and stream prioritization, but it still relies on TCP, unlike newer protocols like HTTP/3, which uses UDP and QUIC.

Exact Extract - Huawei Application Networking Fundamentals:

“HTTP/2 continues to use TCP as its transport layer, introducing improvements like multiplexing over a single TCP connection. UDP-based HTTP/3 is a separate protocol built on QUIC.”

Comprehensive and Detailed Explanation:

Key Factors Affecting FTP Performance:

Tail Drop and TCP Synchronization (A)✅

Tail Dropcauses TCPglobal synchronization, reducing FTP speeds drastically when congestion occurs.

Since FTP isTCP-based, packet loss due to tail drop forcesTCP retransmissions, further degrading performance.

Priority Preemption by Video Traffic (D)✅

UDP-based real-time video trafficis often prioritized overTCP-based trafficto avoid jitter and packet loss.

If video traffic hashigher QoS priority, FTP bandwidth may bepreempted, leading toslow 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 explicitrate limiton FTP traffic.

????Reference:Huawei HCIE Datacom – QoS and Congestion Control

Understanding Huawei OPS and HTTP Communication

????What is Huawei OPS?

HuaweiOpen Programmability System (OPS)enablesAPI-based network automationusing standardHTTP requests.

It supportsNETCONF, RESTCONF, and RESTful APIsfordevice management.

????Why TCP Port 80?

Port 80is thedefault port for HTTP traffic.

Used forweb-based device management, API calls, and telemetry data exchange.

IfHTTPS (secure version) is used, the default port is 443.

Why is the Answer 80?

✅HTTP operates on TCP port 80 by default.

✅Huawei OPS uses HTTP APIs to manage network devices, making port 80 the standard option.

Real-World Application:

Cloud-Native Network Automation:UsesHTTP-based APIs for SDN controllers and automation tools.

Network Device Management:Enablesremote configuration and monitoring over HTTP APIs.

✅Reference:Huawei HCIE-Datacom Guide – Open Programmability System (OPS) & HTTP Communication

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:

1️⃣DHCP Snooping– Protects againstrogue DHCP serversand builds abinding table of legitimate DHCP clients.

2️⃣IP Source Guard (IPSG)– Ensures that onlyauthorized IP-MAC bindingscan send traffic.

Analysis of the Answer Choices:

❌A. DAI + Port Security (Incorrect)

DAI (Dynamic ARP Inspection)prevents ARP spoofingbut doesnot validate IP-MAC-DHCP bindings.

Port Securityonlylimits MAC addresses per portbut doesnot verify IP addresses.

Does NOT protect against unauthorized static IP users.

✅B. DHCP Snooping + IPSG (Correct)

DHCP Snooping:

Preventsrogue DHCP servers from assigning unauthorized IPs.

Builds aDHCP binding table(IP-MAC-Port).

IP Source Guard (IPSG):

Blocks trafficfrom 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 spoofingbutdoes not block unauthorized static IP users.

Lacks IP-level access controlneeded 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 unauthorizedstatic IP users or attackers from accessing VLANs.

Public Wi-Fi Security:Ensures onlyauthorized users receive IPs and can send traffic.

✅Reference:Huawei HCIE-Datacom Guide – DHCP Snooping and IPSG Security Mechanisms

Comprehensive and Detailed In-Depth Explanation:

The regular expression100.$can be broken down as follows:

100:Matches the exact sequence of digits "100".

(dot): Representsany single character.

$:Indicates theend of the line.

Therefore, the pattern100.$matches anyfour-character sequencethat starts with "100" and ends withany single character.

1000 (A): Matches because it has four digits, starting with "100" and ending with "0".

1001 (B): Matches because it has four digits, starting with "100" and ending with "1".

10000 (C): Doesnot matchbecause it hasfive digits.

100 (D): Doesnot matchbecause it only hasthree digits.

Authentication Header (AH) in IPsec

TheAuthentication Header (AH) protocolis part ofIPsecand providesauthentication, integrity, and replay protectionbutdoes NOT provide encryption.

✅B. AH provides data origin authentication.

Ensures thatpackets come from a trusted sourceusing cryptographic signatures.

✅C. AH provides anti-replay protection.

Usessequence numbersto prevent attackers from replaying old packets.

✅D. AH provides data integrity authentication.

Ensuresdata integrityby verifying that packetshave not been tampered withduring 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

IS-IS (Intermediate System to Intermediate System) protocolhas a limit on the size ofLink-State PDUs (LSPs).

Why Fragmentation?

LSPs contain routing and topology information.

If the LSPexceeds the maximum size, fragmentationallows the device to store and forward more routesby breaking them into smaller LSPs.

Key Point:IS-ISfragmentation is essentialin large-scale networks where routing tables grow beyond the default LSP size limit.

✅Reference:Huawei HCIE-Datacom Guide - IS-IS Protocol and Route Scaling

Huawei SD-WAN supports various intelligent traffic steering mechanismsto optimize link utilization andbalance network trafficacross multiple links.

✅D. Traffic bandwidth-based traffic steering

This method ensures that traffic isdistributed across multiple links based on available bandwidth.

SD-WAN dynamically selects linksbased on their real-time bandwidth utilization,ensuring optimal performance and load balancing.