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

InBGP/MPLS IP VPN, whenOSPF is used as the PE-CE routing protocol,Domain IDsare used to determine whether theOSPF routes imported into the VPN instancebelong to the same OSPF domain.

How Domain ID Works in OSPF and MPLS VPN:

Same Domain ID (OSPF Intra-domain routes)

If thePE router's Domain ID matches the OSPF Domain ID, routes aretreated as intra-area routes.

The routes retainOSPF attributeswhen redistributed into the VPN.

Different Domain ID (OSPF Inter-domain routes)

If theDomain ID does not match, routes aretreated as external routes (Type 3 or Type 5 LSAs).

The PE router redistributes these routes asOSPF external routes.

Example Huawei Configuration for Domain ID in OSPF VPN:

ospf 1 vpn-instance VPN1

domain-id 1.1.1.1

This ensuresconsistent OSPF route typeswhen 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

InMPLS LDP (Label Distribution Protocol), label retention modes control how labels are stored in theLabel Forwarding Information Base (LFIB).

DU Label Advertisement Mode (Downstream Unsolicited):

Labels areadvertised to all LDP peers without a request.

The receiving routerdecides which label to usefor forwarding.

Liberal vs. Conservative Label Retention:

✅Liberal Label Retention Mode (Correct Answer)

All received labels from all LDP peers are stored.

Even if apeer is not the optimal next hop, its label is retained.

Allowsfaster convergenceduring failures.

❌Conservative Label Retention Mode

Only the label from the best next-hop peer is stored.

Reduces memory usage but can slow down convergence in case of failure.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS LDP Configuration Guide – Liberal vs. Conservative Label Retention

HCIE-Datacom Training Material – Label Advertisement in MPLS Networks

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.

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:

To supportSR-MPLS (Segment Routing over MPLS),OSPFusesType 10 Opaque LSAsto advertiseSegment Routing (SR) capabilities and information.

Type 10 Opaque LSA (B): Used fordistributing application-specific informationwithin an OSPF area. In SR-MPLS, it carries theSID/Label mappingsand other SR-related information.

Type 7 NSSA External LSA (A):Used to advertise external routes within an NSSA, not related to SR-MPLS.

Type 1 Router LSA (C):Advertises the router’s interfaces and links but does not carry SR-specific information.

Type 2 Network LSA (D):Advertises the links of abroadcast or NBMA network, not used for SR-MPLS.

Therefore, the correct answer isB (Type 10 Opaque LSA), as it enables theadvertisement of SR information.

EVPN Route Types:

Type 1 (MAC/IP Advertisement Route):Advertises host MAC and IP information —used.

Type 2 (MAC/IP Advertisement Route):Advertises MAC + IP binding for end hosts —used.

Type 3 (Inclusive Multicast Ethernet Tag Route):Used to advertise VXLAN multicast group info —used.

Type 4 (Ethernet Segment Route):Used inmulti-homing scenarios, especially inDC (data center) environments, to coordinate DF election —typically not used in campus VXLAN.

So incampus virtualized networks, which are oftensingle-homed,Type 4 is not required.

Correct answer: C. Type 4

X = 0

Y = 0

Z = 1

Understanding MPLS Label Headers

🔹What is MPLS (Multiprotocol Label Switching)?

MPLS is ahigh-performance forwarding technologythat replacesIP lookups with label switching.

Packets are forwardedbased on labels instead of destination IP addresses.

MPLS labels are stacked when passing throughmultiple hops.

🔹MPLS Label Stack Structure

Each MPLS label hasfour fields:

Label– 20-bit identifier used for forwarding.

EXP (Experimental Bits / Traffic Class)– 3-bit field used forQoS (Quality of Service).

S (Bottom of Stack)– 1-bit flag that indicates whether this is thelast (bottom) label in the stack.

TTL (Time-To-Live)– 8-bit field to prevent loops.

Understanding the EXP Fields (X, Y, Z) in the Figure

The image shows a packet with three MPLS labels.

Each label has anEXP field (X, Y, Z) representing the QoS bits.

By default,MPLS EXP bits are copied from the top label to lower labels unless modified by QoS policies.

If no QoS policy modifies the EXP bits, they remain thedefault value of 0.

Thebottom label in the stack (Label 3) often has an EXP value of 1 to indicate specific QoS policies.

Why Are the Answers X = 0, Y = 0, Z = 1?

✅X = 0 (Default EXP for Label 1, the top label in the stack).

✅Y = 0 (EXP for Label 2, unchanged from the default value).

✅Z = 1 (EXP for Label 3, indicating a QoS setting applied to the bottom label).

Real-World Application:

MPLS QoS (Quality of Service):EXP values determinepacket priorityinService Provider networks.

Traffic Engineering (TE):MPLS labels guide packets throughoptimized paths, ensuringlow-latency services.

Enterprise WAN Optimization:MPLS traffic is prioritized forcritical applications like VoIP, Video Conferencing, and Cloud Services.

✅Reference:Huawei HCIE-Datacom Guide – MPLS Label Stack and QoS EXP Field Processing

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

IPsec (Internet Protocol Security) provides secure communication over IP networks by implementing multiple security functions.

✔Data Origin Authentication:

Ensures that the sender of the data is genuine and not impersonated.

Uses techniques such as HMAC (Hash-Based Message Authentication Code).

Correct Match:"The receiver verifies the identity of the sender."✅

✔Data Encryption:

Protects data confidentiality by encrypting packets using AES, 3DES, or other encryption algorithms.

Ensures that only the intended recipient can decrypt the data.

Correct Match:"The sender encrypts the data, and the receiver decrypts the data."✅

✔Data Integrity:

Ensures that data is not altered in transit.

Uses cryptographic hashes (e.g., SHA-256) to verify integrity.

Correct Match:"The receiver verifies received data to determine whether the data has been tampered with."✅

✔Anti-Replay:

Protects against packet replay attacks, where an attacker resends captured packets to disrupt communication.

Uses sequence numbers to detect and reject duplicate packets.

Correct Match:"The receiver rejects duplicate data packets."✅

📖Reference:Huawei HCIE Datacom – IPsec Security Functions