Free Huawei H12-891_V1.0 Practice Exam with Questions & Answers | Set: 3

The Time-To-Live (TTL) field in MPLS is essential for preventing infinite loops and enhancing security.

MPLS TTL Field Functionality:

It prevents packets from circulating indefinitely in the MPLS network.

It allows traceroute (tracert) to identify MPLS hops when TTL propagation is enabled.

Explanation of Correct Answers:✅ B. The processing of IP TTL copy hides the LSR in an MPLS domain, improving security.

If TTL propagation is disabled, MPLS routers do not decrease TTL, hiding internal LSRs from traceroute, enhancing security.

✅ C. MPLS provides two TTL processing modes:

Default Mode: The MPLS TTL copies the IP TTL value when an IP packet enters the MPLS network.

Uniform Mode: The ingress LER sets the MPLS TTL to 255, so it does not decrement.

✅ D. MPLS encapsulation in frame mode supports the TTL field, while cell mode does not.

Frame Mode (Ethernet, PPP, etc.) supports TTL.

Cell Mode (ATM/MPLS) does not support TTL.

Incorrect Answer Explanation:❌ A. If TTL copy is disabled, users can use the tracert function to view MPLS hops.

Wrong! If TTL propagation is disabled, tracert cannot see LSRs inside the MPLS core network.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – TTL Field & Loop Prevention

HCIE-Datacom MPLS VPN Configuration Guide – Traceroute in MPLS Networks

Comprehensive and Detailed In-Depth Explanation:

In VXLAN encapsulation, the data frame is encapsulated as follows:

Original Ethernet Frame: The data packet to be encapsulated.

VXLAN Header: Contains the VXLAN Network Identifier (VNI) and other information.

UDP Header: VXLAN uses UDP (User Datagram Protocol) to transport the encapsulated data over an IP network.

Outer IP Header: Provides the source and destination IP addresses of the VTEPs.

Therefore, the UDP header (C) is encapsulated between the outer IP header and the VXLAN header.

Comprehensive and Detailed Explanation:

✔ 802.1X authentication supports multiple logout mechanisms based on network conditions and security policies.

✔ Correct Logout Modes:

✅ (A) Authentication Server Logout → The RADIUS server can terminate a session.

✅ (B) Manual Logout → Users can disconnect manually.

✅ (C) Access Device Logout → The switch/WLAN controller can enforce logouts (e.g., if inactivity is detected).

✔ Why Not (D)?

❌ (D) Accounting Server Logout → The accounting server tracks session usage but does not enforce logouts.

???? Reference: Huawei HCIE Datacom – 802.1X Authentication & Session Termination

Huawei Switch Deployment Methods in CloudCampus

✅ A. DHCP Option 148 – Used for automatic device registration in iMaster NCE-Campus.

✅ B. CLI (Command-Line Interface) – Traditional manual configuration method using the command-line interface.

✅ C. Web Interface – Web GUI-based configuration for easy management.

✅ D. Huawei Registration Center – Cloud-based automatic registration and provisioning for 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 Huawei’s Free Mobility solution:

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

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

Key points:

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

B is incorrect — AP and PEP can be on separate devices, offering deployment flexibility.

C is incorrect — The policy enforcement happens at the PEP, not the AP. AP ' s job is to authenticate and tag traffic.

D is correct — AP and PEP can be deployed on different devices.

Correct answers: A, D

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

BGP in Huawei SD-WAN

Huawei SD-WAN uses BGP (Border Gateway Protocol) as the primary routing protocol to 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 allows traffic engineering and policy control across SD-WAN tunnels.

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

Comprehensive and Detailed In-Depth Explanation:

To support SR-MPLS (Segment Routing over MPLS), OSPF uses Type 10 Opaque LSAs to advertise Segment Routing (SR) capabilities and information.

Type 10 Opaque LSA (B): Used for distributing application-specific information within an OSPF area. In SR-MPLS, it carries the SID/Label mappings and 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 a broadcast or NBMA network, not used for SR-MPLS.

Therefore, the correct answer is B (Type 10 Opaque LSA), as it enables the advertisement of SR information.

Comprehensive and Detailed In-Depth Explanation:

The free mobility function in iMaster NCE-Campus allows users to maintain consistent security policies regardless of their physical location within the campus network. To correctly implement this function, the administrator must:

A. Define security groups: Group users and devices based on roles or functions.

B. Deliver the inter-group policy: Apply policies that define how different security groups interact.

C. Deploy a policy control matrix: Establish a matrix that specifies the access control policies between security groups.

D. Select the policy enforcement point: Choose devices or interfaces where policies are enforced, such as switches or routers.

All four steps are crucial for achieving dynamic policy enforcement in a virtualized and mobility-oriented campus network.