H12-891_V1.0 Exam Results

In Intermediate System to Intermediate System (IS-IS), the cost (metric) determines the preferred routing path. The cost is assigned to each interface, and IS-IS uses the shortest path (lowest cost) to reach a destination.

The correct command to manually modify the IS-IS interface cost is:

kotlin

CopyEdit

interface GigabitEthernet 0/0/1

isis enable 1

isis cost

Where represents the manually configured cost of the interface.

Incorrect Options:

A. isis circuit-type – Used to define the circuit type (Level-1, Level-2, or both), but does not affect cost. ❌

B. isis timer hello – Modifies the hello interval for IS-IS neighbors but does not change cost. ❌

C. isis circuit-level – Not a valid IS-IS configuration command. ❌

Reference from Huawei HCIE-Datacom Documentation:

HCIE-Datacom Certification Guide – IS-IS Protocol Configuration

Huawei Command Reference for IS-IS

Huawei Routing & Switching Training Manual – IS-IS Cost Metric Adjustment

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

Route Target (RT) is a BGP extended community attribute used in MPLS Layer 3 VPNs (L3VPNs) to control the import and export of VPN routes between different VPN instances (VRFs).

Explanation of Correct Answers:

✅ A. Each VPN instance is associated with one or more pairs of VPN Target attributes, used to control VPN routing information advertisement and reception between sites.

Each VRF (VPN Routing and Forwarding instance) has an associated RT that determines which routes are imported and exported between VPNs.

RTs enable inter-VPN communication while maintaining separation between VPN customers.

✅ B. Export Target and Import Target are independent of each other and support multiple values to implement flexible VPN routing information advertisement and reception control.

The Export RT specifies which routes should be advertised.

The Import RT specifies which routes should be accepted into a VRF.

These can be configured independently to control traffic flow between VPNs.

✅ C. RTs are classified into two types: Export Target and Import Target.

Export Target: Defines which VPN routes are advertised.

Import Target: Defines which VPN routes are accepted.

A VPN instance can have multiple RTs to allow flexibility.

✅ D. The RT value is advertised to neighbors through the BGP extended community attribute in Update messages.

RTs are carried in BGP UPDATE messages as part of the BGP extended community attribute, enabling VPN route exchange between PEs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Route Target (RT) Concepts

HCIE-Datacom Study Material – BGP Route Advertisement in MPLS VPNs

Telemetry Data Collection in Huawei Devices

Telemetry allows real-time streaming of network performance data based on predefined sampling paths. Supported sampling paths include:

✅ A. Interface statistics

Monitors real-time traffic usage, errors, and packet loss on interfaces.

✅ C. CPU information

Tracks CPU utilization and performance metrics.

✅ D. Memory information

Monitors RAM usage and system memory consumption.

Incorrect Answer:

❌ B. Information about the optical module on an interface

Telemetry does not natively support direct optical module monitoring; instead, SNMP or CLI commands like display transceiver are used.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Supported Sampling Paths

HCIE-Datacom Study Material – Network Performance Monitoring with Telemetry