Huawei H12-831_V1.0 Dumps Questions Answers

Comprehensive and Detailed In-Depth Explanation:

Understanding the BGP Network Topology in the Question:

EBGP Peering & Route Distribution

Each router forms EBGP peer relationships with directly connected neighbors.

BGP learns and propagates routes via EBGP neighbors.

R1 and R4 advertise the static route 192.168.1.0/24 into BGP.

Effect of the aggregate 192.168.1.0/16 detail-suppressed Command on R2

R2 performs BGP route aggregation, summarizing 192.168.1.0/24 into a larger 192.168.1.0/16 route.

The detail-suppressed option hides the more specific 192.168.1.0/24 prefix when advertising routes.

As a result, R2 does not advertise the specific 192.168.1.0/24 route to its neighbors.

Route Selection and Traffic Flow Analysis:

R1 and R4 originate 192.168.1.0/24 and advertise it via BGP.

R2 does not advertise the 192.168.1.0/24 route because of the detail-suppressed command.

R3 cannot learn the specific route from R2, so it must choose an alternative path via R5.

R5 learns 192.168.1.0/24 from R1 and advertises it to R3.

Thus, the best available path for R3 to reach 192.168.1.0/24 is R3 → R5 → R1.

✅ Correct Path: R3 → R5 → R1

Checking Each Option:

✅ Option A: R3 → R5 → R1 (Correct)

R3 learns 192.168.1.0/24 from R5, and R5 forwards traffic to R1, which has the static route.

❌ Option B: R3 → R2 → R1 (Incorrect)

R2 does not advertise 192.168.1.0/24 due to route summarization (detail-suppressed), so R3 cannot use R2 as the next hop.

❌ Option C: R3 → R6 → R5 → R1 (Incorrect)

This is an unnecessary detour.

R3 has a direct EBGP connection with R5, so it will use the shortest path (R3 → R5 → R1) instead of going through R6.

❌ Option D: R3 → R5 → R4 (Incorrect)

R3 prefers the shortest AS path to reach 192.168.1.0/24.

Since R1 and R4 both advertise the route, R3 will prefer the route via R5 to R1 rather than R4.

Final Conclusion:

✅ A. The correct path for traffic from R3 to 192.168.1.0/24 is R3 → R5 → R1.

Thus, the correct answer is: A.

To determine the correct answer, we need to analyze how OSPFv3 handles Router LSAs (Type 1 LSAs) in a simple Area 0 topology like the one shown in the figure.

1. Understanding OSPFv3 Router LSAs (Type 1 LSAs)

Router LSAs (Type 1 LSAs) are generated by each router within an OSPF area to describe its own directly connected links.

Each router in an OSPF area generates exactly one Type 1 LSA.

The Link-State Database (LSDB) on a router contains LSAs from all routers in the same area.

2. Analyzing the Network in the Figure

There are 3 routers: R1, R2, and R3.

All routers are in OSPFv3 Area 0 (which is a single area).

Each of these routers generates one Router LSA (Type 1 LSA).

Since R2 is in the same area as R1 and R3, its LSDB contains the Router LSAs from itself, R1, and R3.

3. Conclusion

The LSDB of R2 contains 3 Router LSAs (one from each router: R1, R2, and R3).

Final Answer: 3