H12-891_V1.0 VCE Exam Download

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

✅ 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, </tag> closes an element, defining the end of a structure.

✅ C. <?: indicates the start of an instruction.

The declares an XML document and its version/encoding.

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

Closes the XML declaration.

Reference from Huawei HCIE-Datacom Documentation:

Huawei NETCONF Development Guide – XML Formatting Rules

HCIE-Datacom Training Material – Understanding XML in Network Automation

Huawei iMaster NCE-Campus provides open APIs for seamless integration with third-party applications and services. Each API serves a specific purpose in managing network security, operations, analytics, and user interactions.

1. Authentication and authorization → Third-party authentication API

This API is used to integrate third-party authentication systems, such as:

LDAP (Lightweight Directory Access Protocol)

RADIUS (Remote Authentication Dial-In User Service)

OAuth/OpenID authentication

It ensures secure user identity verification, access control, and single sign-on (SSO) in CloudCampus networks.

2. Network O&M → Infrastructure API

The Infrastructure API provides tools for network monitoring, diagnostics, and automated management.

It is used for:

Device status monitoring

Network topology visualization

Fault detection and real-time alerts

Performance optimization

3. LBS (Location-Based Services) → LBS API

The LBS API enables applications to access location data collected by the network.

It is used for:

Tracking users or assets within a campus network

Heatmap generation and movement analytics

Geo-fencing and location-based policies

4. Crowd profiling → VAS API

VAS (Value-Added Services) API is designed for advanced analytics and business intelligence.

It supports:

User behavior analytics

Demographic profiling

Marketing strategies based on network usage patterns

Reference from Huawei HCIE-Datacom Documentation:

HCIE-Datacom Training Guide – CloudCampus Solution

Huawei iMaster NCE-Campus API Documentation

Huawei CloudCampus Solution Whitepaper – Open API and Use Cases

VXLAN networks suffer from ARP flooding because ARP requests are broadcasted across all VTEPs in a Layer 2 domain. To reduce ARP flooding, the following mechanisms can be enabled:

✅ A. Local Proxy ARP

Allows the local VTEP to respond to ARP requests without forwarding them across the VXLAN network.

The VTEP caches MAC-IP mappings and replies directly to ARP requests, reducing unnecessary flooding.

✅ B. ARP Broadcast Suppression

Converts ARP broadcast packets into unicast or multicast packets to minimize network-wide flooding.

✅ C. Host Information Collection

Collects and stores MAC-IP bindings of endpoints, which can be used by proxy ARP to reduce flooding.

Incorrect Answer:

❌ D. Port Isolation

Port isolation prevents communication between devices within the same VLAN but does not help reduce ARP flooding between VTEPs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN Configuration Guide – ARP Optimization Techniques

HCIE-Datacom Training Material – Reducing ARP Broadcasts in VXLAN Networks