Huawei H12-891_V1.0 Exam With Confidence Using Practice Dumps

To automatically enable MPLS on an interface in SR-MPLS:

Segment routing must be enabled globally in the system view → ✅

Segment routing must also be enabled under the IGP process, and IGP (OSPF or IS-IS) must be enabled on the interface → ✅

Clarifications:

SRGB (Segment Routing Global Block) configuration defines SID ranges but does not trigger MPLS enablement → ❌

Static adjacency labels are advanced options and do not auto-enable MPLS → ❌

Correct answers: B, D

Before performing a network cutover (migration or upgrade), it is essential to collect baseline data to ensure that services operate normally before and after the change.

Importance of Pre-Cutover Information Collection:

Identifies Network Baseline – Helps compare pre-cutover and post-cutover performance.

Detects Hidden Issues – Ensures that no existing network issues interfere with the cutover process.

Prevents Service Interruptions – Ensures all dependent services are accounted for.

Provides Rollback Plan – If issues arise, administrators can restore previous configurations.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Network Change Management Guide – Pre-Cutover & Post-Cutover Best Practices

HCIE-Datacom Training Material – Service Assurance & Risk Analysis

Understanding MPLS Forwarding Mechanism

MPLS (Multiprotocol Label Switching) is a high-performance forwarding mechanism that operates on two planes:

1️⃣ Control Plane:

Establishes Label Switched Paths (LSPs) using protocols like LDP (Label Distribution Protocol), RSVP-TE (Resource Reservation Protocol - Traffic Engineering), or BGP-LU (BGP Label Unicast).

Assigns labels to packets based on routing policies.

2️⃣ Data Plane (Forwarding Plane):

Uses a Label Forwarding Information Base (LFIB) instead of traditional IP routing.

Packets are forwarded based on labels, not IP addresses.

Analysis of the Answer Choices

✅ C. The system automatically assigns an ID to the upper-layer application that uses a tunnel. This ID is also called the tunnel ID.

Correct: MPLS assigns a Tunnel ID to applications that utilize tunnels (e.g., VPNs, MPLS-TE, or L2/L3 services).

This ID helps differentiate between various tunnel applications, ensuring traffic follows the correct LSP.

❌ A. After an IP packet enters an MPLS domain, the MPLS device forwards the packet based on FIB table queries.

Incorrect: MPLS routers do NOT use the FIB (Forwarding Information Base) for forwarding once labels are assigned.

Instead, they use LFIB (Label Forwarding Information Base) to switch packets based on labels.

❌ B. If the tunnel ID is 0x0, the MPLS forwarding process starts.

Incorrect: If the Tunnel ID is 0x0, MPLS does NOT start; it means no label is assigned, and traditional IP forwarding occurs.

❌ D. If the tunnel ID is not 0x0, the normal IP forwarding process starts.

Incorrect: If the Tunnel ID is not 0x0, MPLS forwards traffic using label switching, not IP forwarding.