H12-891_V1.0 Exam Dumps : HCIE-Datacom V1.0

Huawei Open Programmability System (OPS) is a programmable network architecture that uses RESTful APIs. In RESTful operations:

GET → Retrieve data

PUT → Configure/replace the value of a managed object

POST → Create new resources or perform non-idempotent operations

PATCH → Partially update a resource

When configuring or updating the value of a managed object (fully replacing it), PUT is the correct method.

Exact Extract – Huawei OPS and RESTful API Guide:

“The PUT method is used to configure the value of a managed object, replacing the entire object if it exists.”

In SR-MPLS (Segment Routing over MPLS), prefix SID conflicts may occur if multiple prefixes are assigned the same SID or vice versa.

Conflict resolution principle (Huawei standard):

When there are multiple SIDs for the same prefix, the SID with the lowest value wins.

When the same SID is assigned to multiple prefixes, the prefix with the smallest address wins.

Apply to this case:

Conflict: Two entries for 1.1.1.1/32 with SID 2 and SID 1.

SID 1 is lower, so 1.1.1.1/32 → SID 1 is selected.

Correct answer: D. 1.1.1.1/32 → SID 1

VRRP (Virtual Router Redundancy Protocol) and Flapping

VRRP ensures gateway redundancy by allowing multiple routers to work together as a virtual router. Flapping occurs when the master and backup routers frequently switch roles.

Causes of VRRP Flapping:

✅ A. Too small interval between Advertisement packet transmissions – Can cause flapping

If the Advertisement interval is too short, frequent VRRP state changes can occur.

✅ C. Packet loss on an interface of the backup device – Can cause flapping

If the backup router loses VRRP packets, it might assume the master is down and initiate an election.

✅ D. Flapping on the link transmitting VRRP Advertisement packets – Can cause flapping

If the link used for VRRP experiences instability, packets may be lost, triggering VRRP role changes.

Incorrect Answer Explanation:

❌ B. Inconsistent preemption delay settings – Does NOT cause VRRP flapping

Preemption delay only affects when a router takes over as master after recovering from a failure.

It does not directly cause flapping because the role change happens only after a delay, preventing frequent transitions.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VRRP Configuration Guide – Preventing VRRP Flapping

HCIE-Datacom Study Material – VRRP Timers and Stability