Free Practice Questions for Huawei H12-891_V1.0 Exam

Huawei’sSD-WAN solutionoffers a full suite of application optimization technologies, including:

Application identification: Uses DPI and traffic signatures to identify applications.

Intelligent traffic steering: Dynamically routes traffic based on application type and real-time link performance.

WAN optimization: Reduces latency, deduplicates traffic, and optimizes throughput for key apps.

QoS: Prioritizes critical applications and ensures bandwidth guarantees.

All listed options are part of the Huawei SD-WAN solutionfor optimizing user experience and application performance.

Correct answers: A, B, C, D

Comprehensive and Detailed In-Depth Explanation:

BGP4+ (BGP for IPv6) uses theMP_REACH_NLRI(Multiprotocol Reachable Network Layer Reachability Information) attribute to advertise IPv6 routes. This attribute is part of BGP's multiprotocol extensions (RFC 2858), allowing BGP to support multiple address families, including IPv6.

MP_REACH_NLRI:Advertises reachable IPv6 prefixes along with next-hop information.

MP_UNREACH_NLRI:Used to withdraw previously advertised IPv6 routes.

Since IPv6 addresses are significantly different from IPv4 addresses in structure and length (128 bits), the traditional BGP update message format (which supports only IPv4) is insufficient. TheMP_REACH_NLRIattribute solves this by carrying IPv6-specific information.

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.

SRv6 Instruction Naming Conventions

SRv6 (Segment Routing over IPv6)uses segment identifiers (SIDs) with specific functions, indicated byinstruction keywords:

✅A. T: Searches a specified routing table to forward packets.

T (Table Lookup)→ Performsa lookup in a specified routing tableand forwards packets accordingly.

❌B. M: Searches a Layer 2 forwarding table for unicast forwarding.

Incorrect!SRv6 does not use M for Layer 2 unicast forwarding.

✅C. V: Searches a VPN instance routing table to forward packets.

V (VPN Routing Table Lookup)→Performs a lookup in a VPN instance (VRF) tablefor forwarding.

✅D. X: Forwards packets through one or a group of specified Layer 3 interfaces.

X (Cross-connect forwarding)→Forwards packets via a specified Layer 3 interface or group of interfaces.

Reference from Huawei HCIE-Datacom Documentation:

Huawei SRv6 Configuration Guide – SRv6 SID Naming and Instruction Set

HCIE-Datacom Study Material – Segment Routing over IPv6 (SRv6) Functionality

Comprehensive and Detailed In-Depth Explanation:

1. Understanding VXLAN Asymmetric IRB Forwarding:

InVXLAN (Virtual Extensible LAN)networks, there are two types of IRB forwarding:Symmetric IRBandAsymmetric IRB.

InAsymmetric IRB, routing occurs only at the ingress VTEP (Virtual Tunnel Endpoint).

Theingress VTEP (VTEP1)encapsulates the original data frame and sends it to theegress VTEP (VTEP2)over the VXLAN tunnel.

Thedestination MAC addressof the original Ethernet frame is theMAC address of the Layer 3 gateway (VBDIF)at the egress VTEP.

2. Analyzing the Topology:

PC1 (172.16.2.1/24) withMAC Ais sending traffic to PC2 (172.16.1.2/24) withMAC D.

Both PCs are in different subnets, so inter-subnet routing is required.

VTEP1 (1.1.1.1)on SW1 is the ingress VTEP.

VTEP2 (2.2.2.2)on SW2 is the egress VTEP.

TheVXLAN Network Identifier (VNI)for the traffic is100.

SW1 has two VBDIF interfaces:

VBDIF10 (MAC B)- Interface for BD10 (172.16.2.254).

VBDIF20 (MAC C)- Interface for BD20 (172.16.1.254).

3. Packet Flow in Asymmetric IRB:

Step 1:PC1 sends a packet destined for PC2. The packet is routed at theingress VTEP (SW1)using theVBDIF interface (VBDIF10 with MAC B).

Step 2:Theingress VTEP (SW1)encapsulates the packet in aVXLAN header(VNI 100) and sends it toVTEP2.

Step 3:Theoriginal data frame inside the VXLAN packetmust have adestination MAC addressthat matches thegateway MAC address (VBDIF20 - MAC C)at theegress VTEP (SW2).

Step 4:On reachingVTEP2, the encapsulation is removed, and the original frame withdestination MAC Cis forwarded.

Step 5:VTEP2performs Layer 3 routing to forward the packet toPC2.

4. Why MAC C is Correct:

Inasymmetric IRB forwarding, the routing decision at the ingress VTEP ensures that thedestination MACin the original frame is set to theVBDIF (gateway) MAC of the egress VTEP.

Since theegress VTEP (SW2)hasVBDIF20 (MAC C)for the destination subnet (172.16.1.0/24), thedestination MAC addressof the original frame isMAC C.

The command output shows:

*>i before both networks, which means these routes are the preferred routes (*) and are learned via internal BGP (i).

Two networks are listed: 3002::3 and 3002::4, which means R1does havethese two routes in its BGP IPv6 routing table.

For 3002::4, the path origin shows 65001 i, which means this route originated from AS 65001 and was learned through IBGP.

The AS Path attribute is only shown for 3002::4, but both routes are clearly present.

Therefore, the correct conclusion is:

D. R1 has routes 3002::3/128 and 3002::4/128.

The free mobility solution in Huawei iMaster NCE-Campus allows:

Centralized policy management via the controller

Security group-based policies, decoupled from IPs/VLANs

Automatic policy delivery, no need to configure repeatedly per device

Dynamic mapping of users and IPs via security group subscriptions

Exact Extract - Huawei iMaster NCE-Campus Solution White Paper:

“Free mobility uses security groups and centralized control to enable consistent policy enforcement, avoiding repetitive configurations and simplifying policy management.”

Comprehensive and Detailed In-Depth Explanation:

InHuawei Open Programmability System (OPS), theURL structureis used to specify managed objects in a standardized way.

The URL path/ifm/interfaces/interfaceis used inNETCONF/YANG-based APIsto representinterface-related dataon a device.

This path allows users toquery, configure, or manage network interfacesthrough programmatic means.

TheIFM (Interface Management)model is commonly used for managing network interfaces, and this URL path correctly follows the convention.

Therefore, the statement isTRUE.

When Spanning Tree Protocol (STP) is not enabled on a network, loops can occur in Layer 2 Ethernet networks, leading to various network issues. STP is designed to prevent loops by blocking redundant paths, and its absence can cause broadcast storms, MAC address table instability, and resource exhaustion. Let’s analyze each option in the context of Huawei HCIE Datacom documentation and network behavior:

A. A loop alarm is generated on the LAN switch.

This option is incorrect. Huawei switches, as per HCIE Datacom standards, do not automatically generate a specific "loop alarm" unless configured with loop detection features (e.g., Huawei’s Loop Detection Protocol or similar mechanisms). Without STP or loop detection enabled, the switch may not explicitly generate an alarm for a loop; instead, it will exhibit symptoms like broadcast storms or flapping MAC entries. Therefore, this is not a direct symptom of an STP-less loop. Reference: Huawei HCIE Datacom V3.0 Training Materials, Section 4.2 – Spanning Tree Protocol and Loop Prevention.

B. CPU usage is too high.

This option is correct. When a loop occurs without STP, broadcast packets (and sometimes multicast or unknown unicast packets) circulate endlessly in the network. This leads to excessive processing by switches as they handle these packets, resulting in high CPU usage. Huawei switches, as described in HCIE Datacom documentation, can experience CPU overload due to continuous packet forwarding and processing in a looped environment. Reference: Huawei HCIE Datacom V3.0, Chapter 5 – Switch Performance and Loop Management.

C. MAC entries flap.

This option is correct. In a loop without STP, switches continuously receive frames from multiple ports, causing MAC address tables to update repeatedly as the same MAC address appears on different ports. This "flapping" of MAC entries destabilizes the network and can lead to incorrect frame forwarding. Huawei HCIE Datacom emphasizes MAC address table stability as a critical aspect affected by loops, as outlined in Section 4.3 – Ethernet Switching and Loop Mitigation. Reference: Huawei HCIE Datacom V3.0, Section 4.3.

D. Host receives a large number of broadcast packets.

This option is correct. A loop without STP causes broadcast packets to circulate indefinitely, creating a broadcast storm. Hosts connected to the network will receive an overwhelming number of these packets, potentially leading to performance degradation or even network timeouts. This is a well-documented symptom in Huawei HCIE Datacom training, specifically in discussions about loop prevention mechanisms. Reference: Huawei HCIE Datacom V3.0, Chapter 4 – Layer 2 Loop Prevention.

Thus, the correct symptoms of a loop occurring due to the absence of STP include high CPU usage, flapping MAC entries, and hosts receiving a large number of broadcast packets. Option A is incorrect as it requires specific loop detection configuration, which is not implied in the question.

Comprehensive and Detailed In-Depth Explanation:

In theinter-AS MPLS VPN Option Bsolution:

Option Bestablishes amulti-hop eBGPconnection between the ASBRs (ASBR-PE1 and ASBR-PE2) to exchangeVPNv4 routes.

In this setup, theASBRs exchange labeled VPNv4 routesviaMP-BGP(Multiprotocol BGP).

The command:

[ASBR-PE1-bgp-af-vpnv4] undo peer 10.0.34.4 enable

is used todisable VPNv4 route exchangebetween theASBR-PE1andASBR-PE2.

If this command is executed,ASBR-PE1willnot transmit VPNv4 routestoASBR-PE2, breaking theinter-AS VPN connectivity.

Therefore, the statement isFALSEbecauseASBR-PE1andASBR-PE2mustexchange VPNv4 routes to maintain connectivity between the VPN sites across different ASes.