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

OSPFv3 Configuration Principles:

OSPFv3, the OSPF version supporting IPv6, differs from OSPFv2 in several aspects:

Interface-based Configuration:

OSPFv3 is configured on interfaces directly, unlike OSPFv2 which uses the network command.

Router ID:

The Router ID is still a 32-bit number, typically represented as an IPv4 address.

It must be explicitly specified since OSPFv3 requires a Router ID for operation, even though it supports IPv6.

Analysis:

A. [R1-GigabitEthernet0/0/1] ospfv3 1 area 0:

Correct. This command enables OSPFv3 process 1 on the GE0/0/1 interface in Area 0.

B. [R1-ospfv3-1] router-id 10.1.1.1:

Correct. This correctly sets the Router ID for OSPFv3 process 1.

C. [R1-ospfv3-1-area-0.0.0.0] network 2001:DB8:2345:12::1 ::

Incorrect. OSPFv3 does not use the network command as in OSPFv2. Instead, OSPFv3 is directly configured on interfaces.

D. [R1] router id 10.1.1.1:

Incorrect. The Router ID should be set within the OSPFv3 process view, not the global configuration view.

Therefore, the correct answers are A and B.

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

Comprehensive and Detailed In-Depth Explanation:

BGP4+ (BGP for IPv6) uses the MP_REACH_NLRI (Multiprotocol Reachable Network Layer Reachability Information) attribute to advertise IPv6 routes. This attribute is part of BGP ' s multiprotocol extensions (RFC 2858), allowing BGP to support multiple address families, including IPv6.

MP_REACH_NLRI: Advertises reachable IPv6 prefixes along with next-hop information.

MP_UNREACH_NLRI: Used to withdraw previously advertised IPv6 routes.

Since IPv6 addresses are significantly different from IPv4 addresses in structure and length (128 bits), the traditional BGP update message format (which supports only IPv4) is insufficient. The MP_REACH_NLRI attribute solves this by carrying IPv6-specific information.