Huawei H12-891_V1.0 HCIE-Datacom V1.0 Exam Practice Test

Comprehensive and Detailed In-Depth Explanation:1. Understanding SRv6 (Segment Routing over IPv6):SRv6 uses theIPv6 headeralong with an additionalSRH (Segment Routing Header)to implement segment routing within an IPv6 network. The SRH contains:Segment List (SL):A list of IPv6 addresses (segments) to traverse.SL (Segments Left):An integer that indicates thenumber of segmentsyet to be visited.Active Segment:Thenext IPv6 addressin the segment list, stored in theDestination Addressfield of the IPv6 header.2. Analyzing the Given Scenario:Thesegment list (SL)in the SRH header shows:FC04::400FC04::4FC03::3The segment list is processed inreverse order(from bottom to top).SL (Segments Left)indicates theindex of the active segmentin the list.TheDestination Addressin the IPv6 header is currentlyFC04::4, indicating that theactive segmentis thesecond elementin the list.3. Determining the Value of SL:Theindexingin the segment list starts from0.SinceFC04::4is thesecond segment (from the bottom), the value ofSLwill be1.This means that1 segment is leftto be processed after the current one (FC04::4).Once the packet reachesFC04::4, theSL value will decrement to 0, and the next segment (FC03::3) will be processed.4. Why the Answer is 1:TheSL value decreases as segments are processed.As the currentactive segmentis thesecond in the list (from the bottom), theSL value is 1.

In BGP4+ (used for IPv6 routing), the MP_REACH_NLRI attribute is used to advertise reachable routes. The Next Hop field must:

Contain a global unicast IPv6 address

Link-local addresses are not used in MP_REACH_NLRI because they are valid only on a local link and not suitable for inter-AS routing.

RFC 2545 (Multiprotocol Extensions for BGP-4) also states that the Next Hop must be a routable global address.

Therefore:

C. It must be a global unicast address — is correct.

The other options involving link-local addresses are incorrect.

Comprehensive and Detailed In-Depth Explanation:

Telemetry in a narrow senserefers specifically to thedevice-side telemetryprocess, which includes the following key modules:

Data generation (A):The device collects and generates telemetry data, such as performance metrics or operational statistics.

Data push (B):The deviceactively pushes the collected datato the configured destination (such as a collector or management system) using a data streaming protocol.

Data source (C):The entity on the device that generates or provides themonitored data.

Data subscription (D)isnot part of the device-side telemetry; it is related to themanagement system side, where users subscribe to specific telemetry data streams.

Therefore, the correct answers areA, B, C.

Comprehensive and Detailed In-Depth Explanation:

Prefix Segment:

Represents adestination prefixin the network.

APrefix SID (Segment Identifier)is a globally unique SID that maps to anIP prefixand is within theSRGB (Segment Routing Global Block)range.

Therefore,Cis correct.

Ais incorrect because a prefix SIDis within the SRGB range, not out of it.

Adjacency Segment:

Represents alink (adjacency)between two nodes.

AnAdjacency SIDislocally significantand typically allocated from theSRLB (Segment Routing Local Block)range.

It uniquely identifies a link between nodes in thesource node’s local routing table.

Therefore,Dis correct, whileBis incorrect because an adjacency SID is not necessarily an offset within the SRGB.

MP-BGP is an extension of BGP-4 that supports multi-protocol address families such as IPv6, VPNv4, etc. When PE and CE exchange BGP routes, there is no need to create a BGP process per VPN on the CE. The CE typically runs a standard BGP process, while the PE maintains separate VPN routing tables (VRFs).

Exact Extract - Huawei HCIE-Datacom MP-BGP Chapter:

“CE devices use standard BGP, and multiple VPNs can share the same BGP process on the CE. The PE handles VPN route separation through VRFs and MP-BGP.”

A screenshot of a computer AI-generated content may be incorrect.

Comprehensive and Detailed In-Depth Explanation:

1. Portal Authentication:

Scenario:Guests who move frequently and use different types of terminals.

Portal authentication (also known as Web authentication) is commonly used in environments like Wi-Fi hotspots, hotels, and public areas.

Users are redirected to a login page where they enter credentials.

This method is flexible for guests and visitors who may frequently change locations or devices.

Use Case:Wi-Fi access for guests in a corporate environment.

2. MAC Address Authentication:

Scenario:Dumb terminals such as printers and fax machines.

MAC address authentication is useful for devices that do not support interactive authentication methods (like printers or IP phones).

It authenticates devices based on theirMAC addresswithout user intervention.

This method is suitable for static, non-user devices that are typically part of the local network.

Use Case:Ensuring that only authorized printers or IP phones connect to the network.

3. 802.1X Authentication:

Scenario:Office users in scenarios demanding high security.

802.1X is aport-based network access control protocolthat authenticates users before allowing network access.

Typically used in wired or wireless LAN environments where high security is required.

It usesEAP (Extensible Authentication Protocol)methods and integrates with RADIUS servers.

Use Case:Corporate LAN environments with stringent security policies.

Let's dissect each option based on OSPFv3 LSA behavior from Huawei HCIE Datacom documentation.

✅ Option A: Correct

OSPFv3 uses Router LSAs (Type 1) to describe the local interfaces, links, and neighbors.

R1, as part of Area 0, will generate Router-LSAs and receive Router-LSAs from neighbors in the same area (R2 and R3 via switch S1).

Huawei Datacom Reference:

"Each OSPFv3 router originates a Type 1 Router LSA for each area it belongs to."

(Source: HCIE-Datacom Study Guide v3.0 - OSPFv3 Fundamentals)

❌ Option B: Incorrect (Correct Answer)

Link-LSAs (Type 8) are not sent between routers. They are only generated for each link on which the router has at least one neighbor. These LSAs are only flooded on the local link.

R1 cannot receive two Link-LSAs from R2 about both links. It can only receive the Link-LSA that R2 generates for the shared link with R1. The other link (e.g., to R4 in Area 1) is irrelevant to R1.

Huawei Datacom Reference:

"A Link LSA is generated by a router for each attached link and is sent only to the routers on the same link."

(Source: HCIE-Datacom Study Guide v3.0 - OSPFv3 LSA Types)

✅ Option C: Correct

On broadcast links, DRs generate Type 2 Network LSAs.

If R3 is the DR on the shared segment (with R1), R1 will have the Network-LSA from R3 in its LSDB.

Huawei Datacom Reference:

"The DR on a broadcast network generates a Type 2 Network LSA to describe all routers on that link."

(Source: HCIE-Datacom Study Guide v3.0 - OSPFv3 LSDB Construction)

✅ Option D: Correct

R2 connects Area 0 and Area 1, hence it's an ABR.

ABRs generate Type 3 Inter-Area-Prefix LSAs to advertise IPv6 prefixes from one area to another.

R2 advertises Area 1 prefixes to Area 0 routers (R1 and R3).

Huawei Datacom Reference:

"Inter-Area-Prefix LSAs (Type 3) are generated by ABRs to advertise IPv6 prefixes from one area into another."

(Source: HCIE-Datacom Study Guide v3.0 - ABR Functionality in OSPFv3)

According to the displayed OSPF error statistics from the Huawei device, the key HELLO packet error shown is:

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2 : Netmask mismatch

This indicates that the OSPF adjacency formation is failing due to a subnet mask mismatch between the two OSPF neighbors on the corresponding interface (GigabitEthernet 0/0/0). OSPF uses the subnet mask in Hello packets to ensure that neighbors are in the same network. If the masks do not match, OSPF will not form an adjacency.

From the Huawei Official HCIE-Datacom Study Guide (Version 3.0) — under the OSPF Troubleshooting Section:

"Netmask mismatch: If the subnet mask configured on the interfaces of OSPF neighbors does not match, a 'Netmask mismatch' error occurs. OSPF requires neighbors to be on the same subnet to establish an adjacency. This is a common reason for failure in adjacency formation."

(Reference: Huawei HCIE-Datacom V3.0, OSPF Troubleshooting Chapter, Section 4.2 – OSPF Hello and Adjacency Establishment Issues)

Thus, among the given options:

A. Area type inconsistency would result in an area ID mismatch error, not netmask.

B. Authentication mismatch would show a bad authentication key or type error.

D. Hello interval mismatches would trigger a Hello timer mismatch error.

Only C. The IP address masks of the interfaces are inconsistent directly matches the actual error observed: Netmask mismatch.

ForOSPF neighbors to reach Full state, they must exchangeLSAs (Link State Advertisements) properlyand synchronize their databases.

Possible Causes Preventing OSPF from Entering Full State:

✅A. A link works abnormally

If thephysical or Layer 2 linkis unstable,OSPF Hello packetsmay be lost, preventing the Full state.

✅B. The OSPF network types on both ends of the link are inconsistent

OSPF network types (Broadcast, P2P, NBMA, etc.) must matchon both ends.

Example: If one router isP2Pand the other isBroadcast, adjacency issues occur.

✅C. The router IDs of neighbors are the same

Router ID conflicts prevent OSPF adjacencies from forming.

Each router must have aunique Router ID.

✅D. The OSPF MTU values of interfaces on both ends of the link are different

If MTU settings do not match,OSPF Database Description (DD) packets may be dropped, preventing Full state.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPF Configuration Guide – Troubleshooting OSPF Neighbor Issues

HCIE-Datacom Study Material – OSPF Adjacency and Route Synchronization

BGP in Huawei SD-WAN

Huawei SD-WAN usesBGP (Border Gateway Protocol) as the primary routing protocolto exchange VPN routes between Customer Premises Equipment (CPEs) and the controller.

✅Why BGP is Used in SD-WAN?

Scalability: BGP can handle a large number of VPN routes.

Policy-Based Routing: BGP allowstraffic engineering and policy controlacross SD-WAN tunnels.

Multiprotocol Support: Huawei SD-WAN usesMP-BGP to exchange IPv4, IPv6, and VPNv4 routes.

SR-MPLS leverages IGP (OSPF/IS-IS) extensions to advertise Segment IDs (SIDs) and can also integrate with TE (Traffic Engineering) for bandwidth reservation using RSVP-TE or SR-TE.

Exact Extract – Huawei SR-MPLS Configuration Guide:

“SR-MPLS uses extensions in IGP to distribute label bindings and, combined with traffic engineering, supports bandwidth assurance and high-bandwidth services.”

Error analysis:

The error SSLError and CertificateError indicates the server's SSL certificate'shostname doesn't match the IP addressbeing used in the request.

This happens when acertificate is issued for a domain (like devzone.huawei.com), but the client accesses it via an IP address (139.9.213.72), causing atrust failure.

Correct statements:

A—✅: The client doesn't trust the SSL certificate → correct.

B—✅: SSL verification fails due to hostname mismatch.

C—✅: Disabling verification with verify=False bypasses the check (only recommended in lab/testing environments).

D—❌: Uses http instead of https, which changes protocol and defeats the purpose of SSL. Also uses POST without API path.

Correct answers: A, B, C

GRE (Generic Routing Encapsulation)supports encapsulation of many protocol types:

SupportsIPv4 and IPv6 unicastencapsulation —✅

Doesnot support IPv6 broadcastencapsulation. GRE doesn’t natively handle multicast or broadcast IPv6 traffic well —❌

It is a lightweight tunneling protocol and relativelyeasy to deploy, placing minimal overhead on devices —✅

Correct answer: C. GRE can encapsulate IPv6 broadcast packets— is incorrect.

BGP EVPN Route Types in VXLAN:

BGP EVPN Type 2 Route (MAC/IP Advertisement Route)

Used forhost reachability advertisement.

Carries MAC and IP address information of endpoints.

Does not carry an IP Prefix field(Type 5 routes handle prefixes).

Correct Explanation of Answer Choices:✅IP Address (B) is included– Used for host mobility and reachability.✅L3VNI (C) is included– Used forLayer 3 VXLAN routing.✅L2VNI (D) is included– Used forLayer 2 VXLAN bridging.❌IP Prefix (A) is not included in Type 2 routes– It is part ofEVPN Type 5 routesforprefix advertisement.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – Type 2 vs. Type 5 Routes

HCIE-Datacom Training Material – VXLAN Overlay Networks and BGP EVPN

Congestion Avoidance in Networking

Congestion avoidance mechanismsprevent packet loss and delayby managing queues before congestion occurs.

Common Congestion Avoidance Techniques:

Weighted Random Early Detection (WRED)– Randomly drops low-priority packets before congestion builds up.

Explicit Congestion Notification (ECN)– Marks packets instead of dropping them to signal congestion.

Queue Management– Techniques likepriority queuing (PQ) and weighted fair queuing (WFQ)help prevent congestion.

Reference from Huawei HCIE-Datacom Documentation:

Huawei QoS Configuration Guide – Congestion Avoidance Technologies

HCIE-Datacom Study Material – Traffic Management and Queue Optimization

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

On the2.4 GHzband, onlythree non-overlapping channelsexist:1, 6, and 11.

Inhigh-density WLAN scenarios, channels like1, 5, 9, and 13can be used withlower transmit powerto reduce co-channel interference — though they slightly overlap, they can work in dense deployments when managed properly.

On the5 GHzband, there are many non-overlapping channels. It’s recommended tostagger high and low channelsamong adjacent APs toavoid interference.

Correct answer: A. TRUE

Comprehensive and Detailed In-Depth Explanation:

TheStrict Priority (SP) scheduling algorithmalways gives preference to high-priority queues.

A:Correct. SP scheduling may lead toqueue starvationbecause low-priority queues might never get serviced if high-priority traffic is constant.

B:Correct. SP always schedules thehighest-priority queue first.

C:Correct. Among multiple low-priority queues, if SP is combined with FIFO (First In, First Out), packets that arrive first are forwarded first.

D:Incorrect. The SP algorithmdoes not guarantee minimum bandwidthfor lower-priority queues. It prioritizes high-priority queues regardless of bandwidth configuration, which can lead to starvation of lower-priority traffic. To ensure minimum bandwidth, aWeighted Fair Queuing (WFQ)orCBWFQ (Class-Based Weighted Fair Queuing)algorithm would be more suitable.

In OSPFv3 (used for IPv6), Link LSAs (Type 8) are not advertised throughout the entire area. Instead, they are only advertised on a specific link (i.e., the local link). This differs from OSPFv2, where LSAs like Type 1 or Type 2 are advertised across the area.

Exact Extract - Huawei HCIE-Datacom V1.0 Courseware - Chapter: OSPFv3 Operation

“Link LSAs are generated by routers for each attached link and sent only on that link, not flooded throughout the area.”

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.”

InHTTP status codes:

401 Unauthorized: The server has received the request butrequires authentication. This typically means:

No token or credentials were provided.

Credentials/token were incorrect or expired.

Other options:

403 (Access Denied)would mean correct credentials butinsufficient permissions.

404: Resource does not exist.

503: Service unavailable.

Correct answer: A. Unauthorized

Link-LSA (Type 8)in OSPFv3 performs the following:

Advertises therouter’s link-local addressto neighbors.

Advertises therouter’s interface IDon the link.

CarriesIPv6 prefixesassociated with the interface (since Router LSA no longer does this in OSPFv3).

TheOptions field in Link-LSAcontainscapabilities of the originating router,notthe options from Network-LSA.

So,Option D is incorrect— the Link-LSA doesnot advertise options from the Network-LSA.

Correct answer: D

Huawei’sNetwork Access Control (NAC)Portal authentication supports various identity authentication methods for user login via a web page. These include:

Username and password— standard method.

Passcode— one-time password or PIN.

SMS verification code— users receive a dynamic code via SMS for identity verification.

However:

MAC addressauthentication is used inMAC-based authentication, not Portal. MAC authentication allows a device to be authenticated using its MAC address without user interaction (i.e., not via a Portal page).

Correct answer: D. User’s MAC address

Comprehensive and Detailed In-Depth Explanation:

AfterPortal authenticationon a wireless network, the following parameters can be used for authorization:

free-rule (A):Allows traffic even before authentication.

UCL (B):User Control List, specifying user permissions.

ACL (D):Access Control List, defining permitted or denied traffic.

TheIP address (C), however, isnot used as an authorization parameterdirectly. Instead, IP addresses are typically assigned after successful authentication, and the control policies are applied based on user profiles or access lists.

Comprehensive and Detailed In-Depth Explanation:

A. Correct:OPS can use themaintenance assistantto triggerPython scriptsperiodically or based on events.

B. Correct:OPS supportsautomatic deploymentusing Python scripts to download software and configuration files.

C. Incorrect:OPS doesnot inherently provide local storagefor temporarily saving execution results when the network is disconnected. This would require additional programming logic in the script itself, which is not a built-in feature of OPS.

D. Correct:OPS can run scripts toautomatically check device healthand report the status.

Therefore, the incorrect statement isC.

Option A: Correct — both terminal and interface security are important.

Option C: Correct —CAPWAP supports DTLSencryption for secure tunnel communication.

Option D: Correct — intranet security design considersboth wired and wireless.

Option B:Incorrect— traffic suppression (such as broadcast suppression) is implemented usingrate limiting or storm control,not by shutting down interfaces. Shutting down interfaces would disrupt legitimate traffic too.

Correct answer: B

In hot standby (active-active/load balancing) scenarios, Quick Session Backup is critical. This function ensures that session entries are immediately synchronized between firewalls to handle asymmetric traffic (where return traffic goes through a different firewall than the forward traffic).

Without it, the return packet may be dropped due to missing session information on the alternate firewall.

Exact Extract - HCIE-Datacom Security Module:

“When VGMP is in load balancing mode, quick session backup must be enabled to prevent traffic loss due to inconsistent forward and return paths.”

NETCONF definesdatastoresto manage device configurations:

running: Active configuration in use

candidate: Staging area for changes before applying

startup: Configuration loaded on reboot

NETCONF operations:

: Applies changes fromcandidate → running→✅

: Deletes a specified datastore (e.g., startup) →✅

: Validates syntax/logic in thecandidate datastore→✅

Statement D is incorrect: never submits config from startup to running— that’s handled automatically at boot time, not through NETCONF commands.

Correct answer: D

Huawei Open Programmability System (OPS) and HTTP Request Headers

HuaweiOPSallowsnetwork automation and programmabilitythroughHTTP-based APIs. When using Python scripts to sendHTTP requests to network devices, the requestheaders must specify the content formatfor data exchange.

✅B. Content-Type: text/json, Accept: text/json (Correct Answer)

Content-Type: text/json→ Specifies that the request bodycontains JSON-formatted data.

Accept: text/json→ Specifies that theresponse should be in JSON format.

Comprehensive and Detailed In-Depth Explanation:

Analyzing the output:

A. The device sends sampled data every second:Correct. Thesample interval is 1000 ms (1 second).

B. The subscription name is Sub1:Correct. Thesubscription nameis clearly shown asSub1.

C. The subscription mode is static subscription:Correct. Since theSub-stateisPASSIVE, it indicates astatic subscription.

D. The IP address of the device is 192.168.56.1:Incorrect. The IP address192.168.56.1shown in the output is thedestination IPwhere the telemetry data is sent, not the IP address of the device itself.

Comprehensive and Detailed In-Depth Explanation:

In BGP EVPN,Type 2routes (MAC/IP Advertisement routes) are used to advertise:

MAC addressesof endpoints.

ARP entries(MAC-to-IP bindings).

IRB (Integrated Routing and Bridging) routes, allowing the advertisement of both Layer 2 and Layer 3 reachability.

These routes are essential for enabling dynamic VXLAN tunnel establishment and seamless host mobility.

Type 1 (Ethernet Auto-Discovery):Used for multi-homing information.

Type 3 (Inclusive Multicast Ethernet Tag):Used for BUM (Broadcast, Unknown unicast, and Multicast) traffic.

Type 4 (Ethernet Segment):Used for identifying Ethernet segments in multi-homing scenarios.

✅A. encoding: indicates the character set encoding format. Currently, only UTF-8 encoding is supported.

UTF-8 is the default and only supported character encoding in NETCONF XML.

✅B. /: indicates the end of the current tag.

In XML, closes an element, defining the end of a structure.

✅C.

The

✅D. ?>: indicates the end of an instruction.

Closes theXML declaration.

Reference from Huawei HCIE-Datacom Documentation:

Huawei NETCONF Development Guide – XML Formatting Rules

HCIE-Datacom Training Material – Understanding XML in Network Automation

A screenshot of a computer AI-generated content may be incorrect.

InOSPFv3, each LSA type has adefined flooding scope:

Link-LSA (Type 8)

Advertisedonly on the local link

Contains router’s link-local address and prefixes

Scope:Within the local link scope✅

AS-External-LSA (Type 5)

Used to advertiseexternal routes from outside the AS

Flooded across theentire autonomous system, except stub/NSSA areas

Scope:Within an AS✅

Network-LSA (Type 2)

Generated by theDesignated Router (DR)

Describes all routers on a broadcast or NBMA segment

Floodedwithin the originating area

Scope:Within an area✅

Correct Mappings:

Link LSA→Within the local link scope

AS-External-LSA→Within an AS

Network-LSA→Within an area

The Loopback interface is not advertised by default in IS-IS, unless a specific command is used (like network entity with loopback settings or enabling it manually). In this case, the GE0/0/0 and GE0/0/1 interfaces are both UP, and have IS-IS L1/L2 enabled. These two interfaces qualify to advertise IS-IS routes.

Exact Extract - Huawei HCIE-Datacom V1.0 IS-IS Chapter

“By default, only physical interfaces in UP state and configured with IS-IS (L1, L2, or L1/L2) participate in IS-IS. Loopback interfaces must be explicitly advertised using route import policies.”

The incorrect statement is Option C, which says “A site can only belong to only one VPN.” This is false because a single site can belong to multiple VPNs if needed. For example, in some enterprise designs, a site may be part of both the Finance VPN and the Management VPN by configuring multiple routing instances (VRFs) and policies accordingly.

Exact Extract - HCIE-Datacom VPN Technologies Chapter:

“A site may be associated with one or more VPNs, depending on business requirements. This is achieved through VRF and route-target configurations.”

Comprehensive and Detailed In-Depth Explanation:

NSR (Non-Stop Routing)andNSF (Non-Stop Forwarding)are high-availability mechanisms used to maintain network stability during routing process failures:

NSR (Non-Stop Routing):

Operates within thelocal router only.

Keeps routing information synchronized between theactive and standby processes.

Does not require collaboration from neighboring routers.

NSF (Non-Stop Forwarding):

Requires collaboration from neighboring routersthat support graceful restart.

The router undergoing failover relies on its neighbors tomaintain forwarding tableswhile control plane recovery takes place.

Neighboring routers must supportGR (Graceful Restart)for NSF to function correctly.

Therefore, the correct answer isBbecauseNSF requires neighboring router collaboration, whileNSR does not.

Node segments in SR-MPLS (Segment Routing over MPLS) are typically automatically generated and distributed via IGP protocols (such as IS-IS or OSPF) using SR extensions. There is no need to manually configure node segments on every router.

Exact Extract – Huawei HCIE-Datacom Study Guide – Segment Routing:

“Node SIDs are automatically generated and advertised by IGPs with SR extensions. Manual configuration is not required except in special cases like adjacency SIDs.”

Comprehensive and Detailed In-Depth Explanation:

The diagram shows aWAN networkwhereSegment Routing (SR)is used in conjunction with theiMaster NCEcontroller. The network consists ofData Centers (DCs),Branches,Provider Edge (PE)routers, andRoute Reflectors (RR)withinAS 65600. Let's analyze each network technology and its placement in the scenario.

1. BGP-LS (Border Gateway Protocol - Link State):

Application Location:1 (PE to RR)

BGP-LS is used tocollect and distribute network topology informationfrom theIGP (Interior Gateway Protocol)domain.

It enables theiMaster NCE(controller) to learn about the network topology and SR information from PE routers.

The PE routers send theirlink-state informationto theRRusingBGP-LS.

Why Location 1:

The RR collects topology data from PEs and forwards it to the controller for path computation.

2. BGP (Border Gateway Protocol):

Application Location:2 (RR to iMaster NCE)

Standard BGP is used forroute distributionandnetwork connectivity.

The RR usesBGPto exchange route information with thecontroller(iMaster NCE).

Why Location 2:

TheRRaggregates routes and exchanges them with the iMaster NCE for centralized management.

3. MP-IBGP (Multiprotocol Internal BGP):

Application Location:3 (PE to PE)

MP-IBGP is used toexchange VPNv4 and VPNv6 routesbetween PE routers within thesame AS.

It allows PEs toadvertise VPN routesacross thebackbone network.

Why Location 3:

PEs need to communicate VPN-related information within the AS, ensuring end-to-end connectivity between DCs and branches.

4. BGP SR-Policy/PCEP (Path Computation Element Protocol):

Application Location:4 (iMaster NCE to PE)

BGP SR-Policy andPCEPare used by thecontrollertodistribute SR policiesto the PE routers.

TheiMaster NCEcalculates optimal paths and sends the SR policies to PEs viaBGP SR-PolicyorPCEP.

Why Location 4:

The controller programs theSegment Routing pathsdirectly to the PEs for optimal traffic engineering.

Why This Mapping Is Correct:

The mapping is based on theroles and functions of each protocolwithin theSR-based WAN architecture. The controller uses BGP-LS to learn topology, BGP for route reflection, MP-IBGP for VPN route exchange, and BGP SR-Policy/PCEP for path computation and distribution.

There arethree standard inter-AS MPLS VPN options, as per RFC 4364:

Option A (Back-to-Back VRF):

VRFs are directly connected between ASBRs using routing exchange (like static/BGP).

No label switching between ASs —no MPLS label neededbetween ASs.

Option B (EBGP Label Exchange):

ASBRs exchange labeled VPNv4 routes via EBGP.

One MPLS label is required —MPLS forwarding across AS boundaryis used.

Option C (End-to-End LSP):

Full end-to-end LSP is created across ASs.

MPLS labels are definitely usedend-to-end, even between ASs.

Option D (Commonly vendor-specific extensions based on Option B/C):

Similar to Option C —requires MPLS labels.

So:

B. Option B— needs MPLS label✅

D. Option D— also needs MPLS label✅

A. Option A—no MPLS label❌

C. Option C— also uses MPLS label✅, but not listed as an answer option in this question format (should have been).

Assuming valid options areA, B, D, the correct ones needing MPLS labels are:

Correct answers: B, D

Huawei Open Programmability System (OPS) is a programmable network architecture that uses RESTful APIs. In RESTful operations:

GET → Retrieve data

PUT → Configure/replace the value of a managed object

POST → Create new resources or perform non-idempotent operations

PATCH → Partially update a resource

When configuring or updating the value of a managed object (fully replacing it), PUT is the correct method.

Exact Extract – Huawei OPS and RESTful API Guide:

“The PUT method is used to configure the value of a managed object, replacing the entire object if it exists.”

Option B is incorrect because it falsely states that EBGP cannot be configured on Spoke-PE or Spoke-CE if the Hub-CE and Hub-PE run IGP. In reality, EBGP can still be used between Spoke sites and PE devices, regardless of the protocol between the Hub PE and CE. EBGP is often used for PE-CE communication, including in Hub-and-Spoke architectures.

Exact Extract - Huawei HCIE-Datacom VPN Section:

“In Hub&Spoke deployments, EBGP can be deployed between Spoke-CE and Spoke-PE. The choice of routing protocol between Hub-CE and Hub-PE does not limit this.”

Dynamic VLAN Authorization in Huawei CloudCampus

Dynamic VLAN assignmentallows users to be placed into specific VLANsbased on authentication methods, ensuring security and network segmentation.

Correct Explanations:

✅A. Wired users using 802.1X authentication receive VLAN assignments dynamically.

After authentication,the access control system (e.g., iMaster NCE-Campus)assigns VLANs dynamically.

✅C. Wireless users using 802.1X authentication also receive VLAN assignments.

Similar to wired users,wireless 802.1X authentication allows dynamic VLAN assignmentvia the RADIUS server.

✅D. Wired users using MAC authentication can receive VLAN assignments.

If a userdoes not support 802.1X, MAC authentication can still be used to assign VLANs dynamically.

Incorrect Statement Explanation:

❌B. When wireless users pass Portal authentication, they join the authorization VLANs delivered to edge nodes.

Wrong!InPortal authentication, VLAN assignmentis not dynamically deliveredbecausePortal authentication typically applies access policies, not VLAN changes.

Dynamic VLAN assignment is mainly used with 802.1X or MAC authentication.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Configuration Guide – Dynamic VLAN Assignment and Authentication

HCIE-Datacom Training Material – VLAN Authorization in Virtualized Campus Networks

In Huawei’sFree Mobility solution:

Authentication Point (AP): Identifies users and associates them with aSecurity Group Tag (SGT)upon access.

Policy Enforcement Point (PEP): Enforces policiesbetween different security groups, such as allowing or denying traffic.

Key points:

Ais correct — The PEP enforces inter-group access based on defined policies.

Bis incorrect — AP and PEPcan be on separate devices, offering deployment flexibility.

Cis incorrect — Thepolicy enforcementhappens at thePEP, not the AP. AP's job is to authenticate and tag traffic.

Dis correct — AP and PEP can be deployed ondifferent devices.

Correct answers: A, D

Huawei iMaster NCE-CampusWi-Fi Location-Based Services (LBS)useHTTP/HTTPSto send location data (such as AP association, signal strength, timestamp, etc.) to an externalLBS platform.

Thestandard format for such data exchange is JSON (JavaScript Object Notation).

JSON is lightweight, readable, and widely supported by modern web APIs and platforms.

Other options:

XML: Used in legacy systems, heavier format.

HTML: Used for page rendering, not data transfer.

YAML: Used mainly in configurations, not standard for HTTP APIs.

Correct answer: C. JSON

Comprehensive and Detailed In-Depth Explanation:

Analyzing the output:

A. Key authentication is disabled for the tunnel:Correct. The output explicitly states"key disabled".

B. The destination IP address of the tunnel is 10.0.3.3:Correct. The output shows"destination 10.0.3.3".

C. The tunnel is a GRE tunnel:Correct. The output states"Tunnel protocol/transport GRE/IP".

D. Keepalive detection is enabled on the tunnel:Incorrect.The output clearly shows"keepalive disabled".

Therefore, the correct answer isDbecause the tunnel doesnot have keepalive enabled.

802.1X Authentication Overview

802.1X is aport-based authentication mechanismused for secure network access control. It involves:

EAPoL (Extensible Authentication Protocol over LAN) communicationbetween theclient (supplicant) and the switch (authenticator).

RADIUS communicationbetween theauthenticator and the authentication server (AAA server).

✅A. 802.1X authentication uses EAPoL to exchange authentication information.

EAPoL (Extensible Authentication Protocol over LAN)is used to send authentication packets overEthernet (IEEE 802.3)networks.

✅B. In EAP termination mode, the network device terminates EAP packets and re-encapsulates them into RADIUS.

The switchacts as an authentication proxybyterminating EAP sessions and converting authentication information into RADIUS format.

✅C. EAPoL is for wired (802.3), EAPoW is for wireless (802.11).

EAPoL (EAP over LAN) is used in wired Ethernet networks.

EAPoW (EAP over Wireless) is used in Wi-Fi (802.11) networks.

✅D. In EAP relay mode, EAP packets are encapsulated into RADIUS using EAPoR (EAP over RADIUS).

The switchdoes not terminate the EAP sessionbut insteadforwards EAP messages to the AAA server inside RADIUS packets.

Reference from Huawei HCIE-Datacom Documentation:

Huawei 802.1X Configuration Guide – EAPoL, EAPoW, and EAPoR

HCIE-Datacom Training Material – AAA Authentication Modes

Challenges of Static VXLAN Tunnel Configuration

Astatic VXLAN tunnelrequires manualVTEP-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 itdifficult to scale and adjustwhen adding new VTEPs.

✅B. Remote MAC addresses are learned through data flooding

UnlikeBGP EVPN-based VXLAN, whichadvertises MAC/IP bindings through BGP,static VXLAN relies on flooding for MAC learning, causingexcessive traffic.

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

IfN devices need to communicate, each must be manually configured withN(N-1)/2 VXLAN tunnels, leading tohigh administrative overhead.

Incorrect Statement Explanation:

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

Wrong!Static VXLANdoes not use a control plane protocollike 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 In-Depth Explanation:

TheHuawei SD-WAN Solutioninvolves four types of channels to ensure smooth and efficient network operation:

Management Channel (A):Used for managing and monitoring SD-WAN devices. It facilitates communication between theiMaster NCE-Campus controllerand SD-WAN devices.

Control Channel (B):Responsible for transmittingcontrol plane informationsuch as routing updates and protocol control messages.

Data Channel (C):Carries actualuser data trafficover the SD-WAN network.

Orchestration Channel (D):Used forservice orchestration, configuration delivery, and policy management.

All four channels work together to provide comprehensive network management, data transmission, and service orchestration in an SD-WAN environment.

Comprehensive and Detailed In-Depth Explanation:

AnHTTP responsefrom the server to the client typically includes the following components:

Protocol version (C):Specifies the HTTP version used (e.g., HTTP/1.1).

Status code (B):Indicates the response result (e.g., 200 for OK, 404 for Not Found).

Reason phrase (A):A textual description associated with the status code (e.g., "OK", "Not Found").

Headers and Body:Contain additional information and the actual response content.

URI (D):TheUniform Resource Identifieris part of theHTTP requestand not theHTTP response. Therefore,Dis the correct answer.

Comprehensive and Detailed In-Depth Explanation:

When invokingRESTful APIsiniMaster NCE-Campus, the client must include theACCESS-TOKENin therequest headerto authenticate the request.

TheACCESS-TOKENis obtained throughauthenticationand is required forAPI access control.

The correct format in the HTTP header is:

Authorization: Bearer ACCESS-TOKEN

Other formats likeACCEPT-TOKEN,X-ACCEPT-TOKEN, andX ACCESS TOKENare not recognized or valid foriMaster NCE-Campus API requests.

Therefore, the correct answer isA.

Analyzing the Routing Table Output:

The command display ipv6 routing-table protocol isis showsall IPv6 routes learned via IS-IS.

The output shows"Summary Count: 6", meaning R1 hassix IS-IS IPv6 routes.

Explanation of Correct Answers:✅A. R1 has six IS-IS IPv6 routes.

The "Summary Count: 6" confirms thatsix IS-IS IPv6 routes existin R1's routing table.

✅C. IS-IS IPv6 must have been enabled on GigabitEthernet0/0/1 of R1.

Theinterface GigabitEthernet0/0/1is listed as thenext-hop, meaning IS-IS IPv6 must beenabled on that interface.

✅D. R1 is not a Level-1 device.

The protocol is listed as"ISIS-L2", indicating that R1 is anIS-IS Level-2 (backbone) router,not a Level-1 router.

Incorrect Answer Explanation:❌B. R1 does not have IS-IS IPv6 routes.

Wrong!The output clearlyshows six IS-IS IPv6 routes, proving this statement false.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPv6 Routing Protocols Guide – IS-IS for IPv6

HCIE-Datacom Routing & Switching Training – IS-IS L1 & L2 Operations

Huawei IS-IS Configuration Guide – IPv6 Route Management

BGP EVPN in VXLAN Tunneling

✅A. MP_REACH_NLRI is used to carry routing information.

MP_REACH_NLRI (Multiprotocol Reachable Network Layer Reachability Information)is used inBGP updatesto carryVXLAN reachability information.

✅B. Several BGP EVPN routes are defined through BGP extension.

BGP EVPN introduces multiple route types, such asType 2 (MAC/IP Advertisement), Type 3 (Inclusive Multicast), and Type 5 (IP Prefix Advertisement).

✅D. MP_REACH_NLRI is used to carry the RT.

RT (Route Target) defines route import/export policies in VPN environments.

MP_REACH_NLRI carries the RT attributein BGP EVPN updates.

❌Incorrect Answer:

❌C. MP_REACH_NLRI is used to carry the RD.

Wrong!TheRoute Distinguisher (RD)is carriedinside BGP attributes, but not in MP_REACH_NLRI.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – BGP EVPN Route Types

HCIE-Datacom Training Material – VXLAN Dynamic Tunnel Establishment

HuaweiSD-WAN establishes secure tunnels between SD-WAN edge devices (CPEs, AR routers, and controllers) using tunneling protocols.

✅B. GRE over IPsec(Correct Answer)

GRE (Generic Routing Encapsulation) over IPsecisthe primary tunneling method used in Huawei SD-WAN.

GRE provides multi-protocol encapsulation, whileIPsec ensures encryption and security.

Used forsecure communication over public WAN links (e.g., the internet, LTE, MPLS, etc.).

TheMPLS headerconsists of:

Label (20 bits)– Label value used for forwarding.

EXP (3 bits)– QoS field (Class of Service).

S bit (1 bit)– Bottom-of-Stack indicator.

TTL (8 bits)–Time-to-Live, similar to the TTL field in the IP header.

Function of TTL in MPLS:

It is used toprevent infinite loops.

Every LSRdecrementsthe TTL by 1.

When TTL reaches0, the packet isdiscarded.

This mirrors the behavior of IP TTL and ensures loop prevention in MPLS networks.

Correct answer: D. This field is used to prevent packet forwarding loops, similar to the TTL field in an IP header.

In Huawei’s CloudCampus Solution, when static IPsec VPN is used for WAN interconnection, the following devices are capable of acting as egress gateways for encrypted tunnels:

Access Point (AP)

Router

Switch

This is based on Huawei’s CloudCampus architecture, where all three device types can support VPN tunnel termination depending on the deployment size and use case.

Huawei Datacom Reference:

"In static IPsec VPN networking scenarios, egress devices can be APs, Routers, or Switches depending on the deployment model. This allows flexibility for small, medium, and large-scale branches."

(Source: HCIE-Datacom V1.0 Training Guide – WAN Interconnection and VPN Chapter)

Understanding User Authentication Points in a Network

Authentication pointscan be deployed at different network layersbased on security and scalability needs:

✅Access Layer Authentication:

Ensureshigh security & granular control(user-level authentication).

Preferred inhigh-security enterprise networks.

✅Aggregation or Core Layer Authentication:

Reduces authentication overheadbutprovides less granular control.

Suitable forlarge-scale networkswhere authentication load needs to be balanced.

Analysis of the Answer Choices:

✅A. Deploying user authentication points at the access layer achieves granular permission management and high network security.

Correct:Providesfine-grained control per userand prevents unauthorized access.

✅B. Moving user authentication points from the access layer to the aggregation or core layer greatly reduces the number of user authentication points, thereby effectively mitigating the pressure on the AAA server.

Correct:Fewer authentication points meanless load on the AAA server.

✅C. Deploying user authentication points at the access layer has both advantages and disadvantages when compared to doing so at the aggregation or core layer. Policy association can be applied if user authentication points are deployed at the access layer.

Correct:Policy-based authentication isbest applied at the access layerforgranular control.

❌D. When user authentication points are moved from the access layer to the aggregation layer, MAC address authentication for users may fail.

Incorrect:MAC authentication worksat both layers, butpolicy adjustmentsmay be needed.

✅Reference:Huawei HCIE-Datacom Guide – User Authentication Strategies in Enterprise Networks

Comprehensive and Detailed In-Depth Explanation:

OSPFv3, which supports IPv6, uses a router ID that is 32 bits in length, similar to OSPFv2. The router ID in OSPF is always a 32-bit number, typically represented in an IPv4 address format (dotted decimal). Although OSPFv3 is designed to support IPv6, itstill relies on a 32-bit router ID for identification, which must be unique within an OSPF domain. The router ID does not change even though the protocol itself supports IPv6 addresses (128 bits).

Huawei Switch Deployment Methods in CloudCampus

✅A. DHCP Option 148– Used forautomatic device registrationin iMaster NCE-Campus.

✅B. CLI (Command-Line Interface)– Traditionalmanual configuration methodusing the command-line interface.

✅C. Web Interface–Web GUI-basedconfiguration for easy management.

✅D. Huawei Registration Center–Cloud-based automatic registration and provisioningfor plug-and-play deployment.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Deployment Guide – Device Onboarding Methods

HCIE-Datacom Training Material – Zero-Touch Deployment (ZTP) in CloudCampus

In YANG model syntax:

cpu-info can be a list node (✓)

cpu-infos can be a container node (✓)

The sampling path does follow the YANG model hierarchy (✓)

However, the prefix huawei-debug: indicates the YANG module name, not an actual data node. Therefore, debug is not necessarily the top node in the YANG hierarchy — it is a node under the huawei-debug namespace/module.

Exact Extract – Huawei Telemetry and YANG Modeling Guide:

“The format : is used in telemetry to indicate paths. The actual top-level node may differ from the module name.”

Route Target (RT)is aBGP extended community attributeused inMPLS Layer 3 VPNs (L3VPNs)to control theimport and exportof VPN routes between differentVPN instances (VRFs).

Explanation of Correct Answers:

✅A. Each VPN instance is associated with one or more pairs of VPN Target attributes, used to control VPN routing information advertisement and reception between sites.

Each VRF (VPN Routing and Forwarding instance) has an associated RTthat determines which routes areimported and exportedbetween VPNs.

RTs enableinter-VPN communicationwhile maintaining separation between VPN customers.

✅B. Export Target and Import Target are independent of each other and support multiple values to implement flexible VPN routing information advertisement and reception control.

TheExport RTspecifies which routes should be advertised.

TheImport RTspecifies which routes should be accepted into a VRF.

These can beconfigured independentlyto control traffic flow between VPNs.

✅C. RTs are classified into two types: Export Target and Import Target.

Export Target: Defineswhich VPN routes are advertised.

Import Target: Defineswhich VPN routes are accepted.

A VPN instance can have multiple RTsto allow flexibility.

✅D. The RT value is advertised to neighbors through the BGP extended community attribute in Update messages.

RTs are carried in BGP UPDATE messagesas part of theBGP extended community attribute, enabling VPN route exchange between PEs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Route Target (RT) Concepts

HCIE-Datacom Study Material – BGP Route Advertisement in MPLS VPNs

Comprehensive and Detailed In-Depth Explanation:

AnNVE (Network Virtualization Edge) interfaceis responsible for connecting physical or virtual devices to a VXLAN network. It functions as theVTEP (VXLAN Tunnel Endpoint)and supportsencapsulation and decapsulation of VXLAN packets.

Layer 2 VXLAN gateway (D)is used for intra-subnet communication, but theNVE interfaceis the actual point where traffic enters the VXLAN network.

Layer 3 VXLAN gateway (A)is used for inter-subnet communication.

VLANIF interface (C)is used for VLAN-based communication, not directly for VXLAN.

Therefore, theNVE interface (B)is the correct answer as it serves as thetraffic ingress and egress point for the VXLAN network.

Let’s break it down:

A. ❌ Incorrect — Path computation can be done by both controller and ingress routers, not just the controller.

B. ✅ SR-MPLS extends IGP protocols (e.g., OSPF/IS-IS) for segment distribution, allowing smooth evolution.

C. ✅ Supports TI-LFA (Topology Independent Loop-Free Alternate) for fast failure recovery.

D. ✅ Through source routing, SR-MPLS integrates easily with applications for programmable path control.

Exact Extract – HCIE-Datacom Segment Routing Chapter:

“SR-MPLS supports distributed and centralized path computation, uses IGP extensions for deployment, and supports TI-LFA for FRR. It allows interaction with applications through programmable routing.”

A screenshot of a computer AI-generated content may be incorrect.

Comprehensive and Detailed In-Depth Explanation:

ThegRPC-based telemetry protocolutilizesprotocol buffers (.proto files)to define the structure and data format used in communication between a client and a server. In Huawei's telemetry architecture, these files are categorized based on their roles in the data model.

1. RPC Layer:

File:huawei-grpc-dialin.proto

TheRPC layer (Remote Procedure Call layer)handles communication between the client and server.

The filehuawei-grpc-dialin.protodefines thegRPC service interfaces, message structures, and procedures for remote method invocation.

It is essential forestablishing communicationandinvoking telemetry data collection.

Function:Managesdial-in and dial-out connectionsbetween the telemetry client and the server.

2. Telemetry Layer:

File:huawei-telemetry.proto

Thetelemetry layeris responsible forcollecting, packaging, and exporting telemetry data.

The filehuawei-telemetry.protocontains thedata modelused for telemetry reporting, includingstreaming data formatsandtelemetry messages.

It defines how thecollected datais organized and transmitted.

Function:Provides astructured way to export telemetry datain real-time or batch mode.

3. Service Data Layer:

File:huawei-debug.proto

Theservice data layercontains data models related todiagnostics, debugging, and operational data.

The filehuawei-debug.protois used tocollect debugging informationfrom network devices.

This file is crucial fortroubleshooting and monitoring the healthof the system.

Function:Facilitatesdebugging and diagnostic telemetry data collection.

Why This Mapping Is Correct:

The mapping is based on thefunctional role of each layerand thepurpose of each .proto filein the Huawei gRPC-based telemetry architecture.

Correctly identifying the file location is crucial foreffective telemetry configurationanddata collection.

VXLAN tunnel configuration, you donot use a control planelike BGP EVPN. Instead, youmanually configureall necessary forwarding parameters, including:VNI (VXLAN Network Identifier): Identifies the VXLAN segment.VTEP IP Address: The remote tunnel endpoint.Ingress Replication List: Required for multicast emulation (flooding/BUM traffic) in the absence of a multicast control plane.Whenconfiguring statically, theVNIis essential to map Layer 2/3 services to the correct VXLAN segment.Thus, the correct word to complete the sentence is:VNICorrect answer: VNI

Understanding User Isolation in the Same VLAN

In a traditional VLAN,all devices within the same VLAN can communicateunless additional security policies are applied.To isolate users within the same VLAN, the following technologies can be used:

✅B. Port Isolation (Private VLAN or Layer 2 Isolation)

Prevents communication between ports within the same VLAN.

Common in enterprise and campus networksto improve security.

Example:Isolating guest users from employees within the same VLAN.

✅C. IPSG (IP Source Guard)

BlocksIP address spoofingwithin the same VLAN.

UsesDHCP snooping binding tableto verify whether a device is using anauthorized IP address.

✅D. Ethernet Port Security

Limits the number of MAC addressesallowed per port.

Preventsunauthorized devicesfrom communicating within the VLAN.

❌A. Super VLAN (Incorrect Choice)

Super VLANgroups multiple VLANs under a single Layer 3 gateway, but it doesnot provide isolationwithin the same VLAN.

Real-World Application:

Public Wi-Fi Networks:Ensures thatusers within the same VLAN cannot communicatewith each other.

Enterprise Security:Prevents unauthorized access or attacks withinshared VLANs.

✅Reference:Huawei HCIE-Datacom Guide – VLAN Security and User Isolation Technologies

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