Huawei H12-821_V1.0 Exam Dumps

An IP prefix filter is designed to match both the IP address and its prefix length, making it suitable for filtering routing information rather than data packets. Options A and D are incorrect because IP prefix filters do not work directly on data packets, and they can match both prefix numbers and lengths .

BGP Keepalive Message Behavior

Keepalive messages are used to maintain the Established state of a BGP peer relationship.

The Keepalive timer determines the frequency of these messages and defaults to 60 seconds, as per the BGP specification.

HCIP-Datacom-Core Reference

The Keepalive timer default value is covered in the BGP configuration and operational principles.

R3, as the DIS in the Level-2 domain, periodically sends Complete Sequence Number Protocol Data Units (CSNPs) to ensure LSDB synchronization among Level-2 routers.

R1 and R2 are in a Level-1 domain, and IS-IS requires the receiving router (R2) to acknowledge an LSP from R1 by sending a Partial Sequence Number Protocol Data Unit (PSNP).

IS-IS LSPs in a broadcast network are sent using multicast, not unicast, making option C incorrect.

For Level-2 LSPs, acknowledgments are not provided using PSNP by R3; CSNPs are sufficient for synchronization .

In a route-policy, attributes such as MED (Multi-Exit Discriminator) and Local-Preference can be used in apply clauses to influence BGP route selection. Attributes like AS_Path and Tag are typically matched or filtered but not directly applied in the apply clause .

Comprehensive and Detailed Step-by-Step

BGP Origin Attribute Priority:

The Origin attribute determines the source of the route and affects the selection of the best path.

The priority order is as follows:

IGP (i): Highest priority. Routes injected using the network command.

EGP (e): Lower priority. Routes learned from the EGP protocol.

Incomplete (?): Lowest priority. Routes redistributed into BGP from other protocols.

Correct Option:

A: IGP > EGP > Incomplete is the correct order of priority.

HCIA-Datacom Study Guide, Chapter: BGP Path Selection

Huawei BGP Routing Rules