Huawei Updated H12-821_V1.0 Exam Questions and Answers by sid

 LSP Generation in IS-IS

IS-IS routers generate new Link State Packets (LSPs) under the following conditions:

Interface Status Changes : When IS-IS interfaces go up or down, the link state changes, triggering LSP updates.

Periodic Updates : IS-IS periodically regenerates LSPs to ensure link-state information remains synchronized across the network.

Interface Metric Changes : Any modification to interface costs results in a new LSP to reflect the updated cost in the network.

 Incorrect Option

C. Inter-area IP routes change is incorrect because IS-IS does not inherently differentiate between areas for LSP generation.

 HCIP-Datacom-Core Reference

IS-IS LSP generation rules are detailed in the IS-IS configuration and implementation chapters​​.

Comprehensive and Detailed in-depth Step-by-Step Explanation:

OSPF routers establish neighbor relationships and progress through various states during the adjacency formation process. The ExStart state is where routers negotiate the master and slave roles. This negotiation is critical because the master initiates the Data Description (DD) packet exchange process.

Here’s a breakdown of the relevant OSPF states:

ExStart State :

This is the phase where the routers determine which one will act as the master and which will be the slave.

The decision is based on the Router IDs of the two routers. The router with the higher Router ID becomes the master.

Exchange State :

After the master-slave roles are established, the routers exchange DD packets. These packets contain summaries of the LSAs in their respective LSDBs.

2-way State :

This state indicates that bidirectional communication has been established between the two routers, but it occurs before master-slave negotiation.

Init State :

This is an early state where a router has sent a Hello packet to its neighbor but has not yet received a Hello packet in response.

Key Point:

The negotiation of master and slave roles happens exclusively in the ExStart state , making D. ExStart the correct answer.

When a Huawei firewall receives a packet that does not match any existing session table entry, it discards the packet. This is part of the default firewall policy, which ensures that unrecognized traffic is treated as a potential security risk and blocked. This behavior is vital for preventing unauthorized access and mitigating external attacks. The feature aligns with Huawei ' s default security strategies as detailed in their firewall operation manuals ​.

Comprehensive and Detailed In-Depth Explanation:

A. TRUE → EBGP-learned routes can be advertised to both IBGP and EBGP peers .

B. FALSE → BGP uses incremental updates , meaning it only advertises changed routes , not all routes.

C. TRUE → BGP advertises only the best path to prevent unnecessary routing information.

D. TRUE → IBGP split-horizon rule : Routes learned from IBGP peers are not re-advertised to other IBGP peers (to prevent loops).

???? Reference: Huawei HCIA-Datacom Study Guide, BGP Route Advertisement and Split-Horizon Rule.