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

Network Slicing Using Channelized Sub-Interfaces and FlexE

Both channelized sub-interfaces and FlexE (Flexible Ethernet) are used for network slicing, but they have different application scenarios:

✅ A. Channelized sub-interface is recommended for interfaces with bandwidth < 50 Gbit/s.

Channelized sub-interfaces split a physical interface into multiple logical sub-interfaces.

Best for lower-bandwidth links ( < 50 Gbit/s).

✅ B. FlexE is recommended for 50GE and higher-rate interfaces.

FlexE divides a high-bandwidth physical link (e.g., 100GE, 400GE) into multiple virtual slices.

Used in high-speed backbone and data center networks.

✅ C. Only FlexE-based network slicing can be deployed across OTN devices.

FlexE is compatible with Optical Transport Network (OTN) and can be used for long-haul slicing across OTN.

❌ D. Only channelized sub-interface-based network slicing can be deployed across MSTP devices.

Incorrect! While MSTP supports channelized interfaces, FlexE is not restricted to MSTP deployment.

Reference from Huawei HCIE-Datacom Documentation:

Huawei FlexE Technology Whitepaper – Network Slicing in Transport Networks

HCIE-Datacom Training Material – Channelized Sub-Interface and FlexE in Network Slicing

GRE (Generic Routing Encapsulation) has the following benefits:

B. VPN Construction — GRE is often used to build site-to-site VPNs.

C. ARP Encapsulation — GRE supports Layer 2 protocol encapsulation such as ARP.

D. Multicast Support — GRE tunnels can encapsulate multicast packets, unlike traditional IPsec.

A. Enlarging the hop limit is incorrect — GRE does not inherently change TTL or hop behavior; routing protocols still use standard IP processing.

Exact Extract - Huawei HCIE-Datacom Tunneling Chapter:

“GRE can encapsulate multicast and broadcast packets and supports L2 protocols like ARP. It is often used for VPN construction over the internet.”

In MPLS Traffic Engineering (TE), Label Switched Paths (LSPs) can be established:

Statically: Manual configuration.

Dynamically: Typically via RSVP-TE.

Protocol roles:

RSVP-TE: Used to dynamically establish and signal TE LSPs → ✅

OSPF / IS-IS: Act as IGP protocols and provide TE-related link-state information (like bandwidth) but do not establish LSPs themselves → ❌

BGP: Used for route advertisement, not for LSP setup in MPLS TE → ❌

Correct answers: A, C, D

Comprehensive and Detailed In-Depth Explanation:

The telemetry protocol stack is structured as follows:

Communication layer (A): Manages data transmission between the telemetry client (device) and the server.

Transport layer (B): Uses protocols such as gRPC, HTTP/2, or TCP to transmit telemetry data.

Data encoding layer (C): Encodes data using formats like JSON, Protobuf, or XML.

The Data analysis layer (D) is not part of the telemetry protocol stack itself.

Data analysis typically occurs after the data has been collected and received on the server or collector.

Telemetry focuses on data collection, encoding, transport, and transmission, not on analysis.

Therefore, the correct answer is D.

In OSPF:

An NSSA (Not-So-Stubby Area) allows external route injection via Type 7 LSAs.

These Type 7 LSAs are generated by ASBRs inside the NSSA (R4 in this case) when external or direct routes are imported.

ABRs (such as R2) between the NSSA and backbone translate Type 7 LSAs into Type 5 LSAs for flooding into other areas.

Clarification of options:

A: Incorrect — default route is not involved here; it ' s a specific route (10.1.4.4/32).

B: Correct — R2 translates Type 7 LSAs into Type 5.

C: Incorrect — default route is not being advertised.

D: Correct — R4 imports a direct route and generates Type 7 LSAs for it.

Correct answers: B, D

MPLS Positioning in the TCP/IP Model

MPLS (Multiprotocol Label Switching) operates between the Data Link Layer (Layer 2) and the Network Layer (Layer 3).

✅ MPLS is protocol-independent and supports various network layer protocols (IPv4, IPv6, VPN, etc.) by using labels instead of traditional IP routing.

✅ How MPLS Works:

MPLS assigns labels to packets, allowing fast forwarding based on the label rather than a routing table lookup.

Supports Layer 3 VPNs (L3VPNs), Layer 2 VPNs (L2VPNs), and MPLS Traffic Engineering (MPLS-TE).

✅ Why MPLS is Between Layer 2 and Layer 3?

MPLS adds a label between the Layer 2 (Ethernet, PPP) and Layer 3 (IP) headers, effectively creating a separate forwarding mechanism.

Label Switching Routers (LSRs) forward packets based on labels instead of IP addresses, reducing processing time.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – MPLS Architecture and Label Switching

HCIE-Datacom Study Material – MPLS Positioning and Functionality in TCP/IP

Comprehensive and Detailed Explanation:

✔ Hub-Spoke networking is the most efficient and scalable model for interconnecting 100+ branches in a small and midsize campus network.

✔ Why Hub-Spoke?

Centralized Control: A hub router manages communication between spoke routers (branch sites).

Reduced Complexity: Unlike full-mesh, which requires N(N-1)/2* connections, hub-spoke minimizes link costs.

Easier Management: Policy enforcement and security are centralized at the hub site.

✔ Why Not Other Options?

❌ A (Direct Networking) → Suitable for small networks, but inefficient for 100+ branches.

❌ B (Full-Mesh Networking) → High cost and complexity, requiring too many links.

❌ D (Partial-Mesh Networking) → More scalable than full-mesh, but hub-spoke is more optimized for large branch networks.

???? Reference: Huawei HCIE Datacom – WAN Interconnection Models

Comprehensive and Detailed In-Depth Explanation:

An HTTP response from 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): The Uniform Resource Identifier is part of the HTTP request and not the HTTP response. Therefore, D is the correct answer.

Let’s analyze the scenario and each statement carefully based on OSPF path selection and BGP behavior in Huawei routers.

✅ Option A: The preferred path is R1–R3–R4.

According to the OSPF cost values:

R1–R3–R4: Cost = 1 + 1 = 2

R1–R2–R4: Cost = 2 + 2 = 4

OSPF chooses the lowest-cost path to reach a destination. Therefore, R1 will prefer the R1–R3–R4 path to reach 172.20.1.4/32.

Huawei Datacom Reference:

" OSPF selects routes based on the shortest path calculated using link costs. The router always selects the path with the lowest cost. "

(Source: HCIE-Datacom Study Guide v3.0 – OSPF Path Selection, Chapter 5)

✅ Option B: If the stub router on-startup command is run on R3, packet loss occurs during the power-off process of R3 but no packet loss occurs during the startup process of R3.

When R3 is powered off, OSPF needs to reconverge, which causes temporary packet loss.

When R3 starts up, it will advertise itself as a stub router using the stub-router on-startup command. This tells OSPF not to use R3 as a transit path during the startup period, thus preventing traffic blackholing.

Huawei Datacom Reference:

" stub-router on-startup command prevents a newly started router from being used as a transit node by OSPF, allowing routing to remain stable during convergence. "

(Source: HCIE-Datacom Study Guide v3.0 – OSPF Stub Router Functionality, Chapter 6.2)

❌ Option C: The preferred path is R1–R2–R4.

This is incorrect because the OSPF path cost via R2 is higher (4) than the cost via R3 (2).

❌ Option D: Packet loss occurs during both the power-off and startup processes of R3.

Incorrect. As explained above, when the stub-router on-startup command is used, packet loss is avoided during startup, but still occurs during power-off since the alternate path requires convergence.