Huawei H12-891_V1.0 Exam With Confidence Using Practice Dumps

Comprehensive and Detailed In-Depth Explanation:

TheOutbound Route Filtering (ORF)function in BGP allows a BGP speaker to inform its peer about the prefixes that it wants to receive, thereby reducing unnecessary route advertisements.

IP Prefix-List (D)is the correct answer because it is used to define the list of prefixes that are sent to the BGP peer during theORF capability negotiation.

Filter-policy (A)andRoute-policy (B)are used for controlling routing information locally or filtering incoming/outgoing routes but do not directly control the number of routes sent using ORF.

ACL (C)is primarily used for packet filtering and is not related to BGP route filtering.

To analyze this question, let's break down the key concepts and the given LSDB (Link State Database) information from the figure:

Understanding the LSDB Output:

The output shows the OSPF LSDB on R2 with Router ID 10.1.123.2.

Area 0.0.0.0 (Area 0) is displayed along with several Link State Advertisements (LSAs) including Router LSAs, Network LSAs, and Summary LSAs.

Area 0.0.0.1 (Area 1) also displays Router LSAs and a Type 7 LSA (NSSA LSA) with Link-State ID 0.0.0.0.

An External LSA (Type 5) with Link-State ID 0.0.0.0 and AdvRouter 10.1.123.2 is also present.

Analysis of Each Option:

Option A: Area 1 is an NSSA.

Correct.

The presence of a Type 7 LSA (NSSA LSA) in the database indicates that Area 1 is configured as an NSSA (Not-So-Stubby Area).

NSSA allows the injection of Type 7 LSAs for external routes while blocking Type 5 LSAs from entering the area.

Option B: R2 translates Type 7 default route into Type 5 default route.

Correct.

In an NSSA, if an ABR (like R2) has the NSSA ASBR capability, it will convert Type 7 LSAs to Type 5 LSAs before injecting them into the backbone area (Area 0).

In the LSDB, we see both a Type 7 LSA (NSSA) and a corresponding Type 5 External LSA, confirming that R2 performs this translation.

Option C: R2 advertises the default route in the OSPF process.

Incorrect.

There is no indication that R2 itself is originating the default route.

The Type 7 LSA in Area 1 and the Type 5 LSA in Area 0 only indicate translation from another source, not R2 advertising it directly.

Option D: Area 1 does not have Type 3 LSAs. The possible cause is that R2 filters Type 3 LSAs in the outbound direction of Area 1.

Incorrect.

In an NSSA area, Type 3 LSAs (Inter-Area Prefix LSAs) are typically not generated for external routes.

The absence of Type 3 LSAs in Area 1 is due to the nature of NSSA itself rather than any filtering configured on R2.

To automatically enable MPLS on an interface inSR-MPLS:

Segment routing must be enabled globallyin thesystem view→✅

Segment routing must also be enabled under the IGP process, andIGP (OSPF or IS-IS) must be enabled on the interface→✅

Clarifications:

SRGB (Segment Routing Global Block)configuration defines SID ranges butdoes not trigger MPLS enablement→❌

Static adjacency labelsare advanced options and do not auto-enable MPLS →❌

Correct answers: B, D