H12-831_V1.0 Exam Dumps : HCIP-Datacom-Advanced Routing & Switching Technology V1.0

Comprehensive and Detailed In-Depth Explanation:

To determine which statement is false, we need to analyze the IS-IS topology, the role of multi-topology, the IPv6 summary configuration, and the level-1-2 behavior of IS-IS routers. Let’s break it down step by step:

Understanding the IS-IS Topology and Levels:

IS-IS supports multiple levels: Level-1 (L1) for intra-area routing, Level-2 (L2) for inter-area routing, and Level-1-2 (L1-2) routers that can operate in both levels and connect L1 and L2 areas.

In the figure, R1 and R2 are configured as Level-1-2 routers, R3 is a Level-1-2 router, R4 is a Level-1 router, and R5 is a Level-1 router. The area borders are indicated by the system IDs (49.0001 for R4’s area and 49.0002 for R3 and R5’s area).

R4’s Loopback0 has the IPv6 address 2000::/128, which is a host route (a /128 prefix, representing a single address).

Multi-Topology IS-IS for IPv6:

Multi-topology IS-IS allows separate topologies for IPv4 and IPv6, ensuring that IPv6 routes are handled independently. Since multi-topology is enabled on all routers, IPv6 routes (like 2000::/128 on R4) are advertised and processed within the IPv6 topology.

This means that IPv6 routes, including the Loopback0 address of R4 (2000::/128), can be advertised across the IS-IS domain, subject to the level and summary configurations.

IPv6 Summary Configuration (2000::/64 level-1-2):

The command ipv6 summary 2000::/64 level-1-2 is configured in the IS-IS processes of R1 and R2. This command instructs R1 and R2 (as Level-1-2 routers) to summarize the IPv6 prefix 2000::/64 and advertise it to both Level-1 and Level-2 areas.

Summarization means that instead of advertising the more specific route (e.g., 2000::/128 from R4), R1 and R2 advertise the less specific summary route 2000::/64. This summary route covers the 2000::/128 address of R4’s Loopback0.

Since R1 and R2 are Level-1-2 routers, they can advertise this summary to both their Level-1 neighbors (like R4 and R3) and Level-2 neighbors (across areas).

Analyzing Each Statement:

A. The routing table of R1 contains the route 2000::/64.

True. R1 is a Level-1-2 router with the ipv6 summary 2000::/64 level-1-2 command configured. It advertises and installs the summary route 2000::/64 in its routing table, covering the more specific 2000::/128 from R4. Additionally, as a Level-1-2 router, R1 can learn and retain this route from its IS-IS neighbors.

B. The routing table of R2 contains the route 2000::/64.

True. Similar to R1, R2 is also a Level-1-2 router with the same summary command. It advertises and installs the 2000::/64 summary route in its routing table, covering R4’s 2000::/128.

C. The routing table of R3 contains the route 2000::/128.

False. R3 is a Level-1-2 router in area 49.0002, but it receives routes from R2 (a Level-1-2 router in area 49.0001). Because R1 and R2 are configured with the ipv6 summary 2000::/64 level-1-2 command, they advertise the summary route 2000::/64 to their neighbors, including R3. IS-IS prefers the most specific route, but the summary configuration ensures that the more specific 2000::/128 from R4 is not advertised beyond R1 and R2 unless explicitly allowed. Since R3 is in a different area and receives the summary 2000::/64 from R2, it does not have the more specific 2000::/128 route in its routing table. Therefore, this statement is false.

D. The routing table of R2 contains the route 2000::/128.

True. R2, as a Level-1-2 router, is directly connected to R4 (a Level-1 router) via the IS-IS topology. R4 advertises its Loopback0 address 2000::/128 to R2. Even though R2 is configured to summarize 2000::/64, it can still retain the more specific 2000::/128 route in its routing table because IS-IS allows routers to keep both summary and more specific routes, with the more specific route taking precedence for routing decisions.

Conclusion:

The false statement is C, as R3 does not contain the route 2000::/128 in its routing table. Instead, R3 receives the summary route 2000::/64 from R2 due to the summary configuration on R1 and R2.

References to HCIP-Datacom-Advanced Routing & Switching Technology Documents:

HCIP-Datacom-Advanced Routing & Switching Technology V1.0, Section on IS-IS: Multi-Topology IS-IS for IPv6, Level-1 and Level-2 Operations, and Route Summarization.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0, Chapter on IPv6 Routing Protocols: IS-IS Configuration and Behavior, Including Summary Address Commands and L1/L2 Interactions.

This statement is false. In Huawei ' s implementation of BGP Route Reflectors:

Each RR (Route Reflector) and its clients form a cluster identified by a cluster ID.

When an RR reflects a route:

If the Cluster_List is empty, it adds the local cluster ID.

If the Cluster_List already contains values, it adds the local cluster ID to the beginning of the list.

So the RR does modify the Cluster_List by adding its own cluster ID regardless of whether the list is empty or not.

✅ Official Reference from Huawei:

" When an RR reflects a route, it adds its own Cluster_ID to the Cluster_List attribute regardless of whether the Cluster_List is empty or not. This mechanism prevents routing loops. "

— [Huawei HCIA-Datacom Certification Guide – BGP Route Reflector Section]

Comprehensive and Detailed In-Depth Explanation:

1. Understanding the Network Setup

PE1 (Provider Edge 1) is the gateway for network 192.168.1.1/24.

PE2 (Provider Edge 2) is the gateway for network 192.168.2.1/24.

A cloud-based backbone connects PE1 and PE2.

To verify end-to-end communication, engineers need to check reachability between PE1 and PE2.

2. Evaluating Each Answer Option

Option A: " Configuring NQA on PE1 and PE2, with the destination address being the IP address of each other. "

✅ Correct.

NQA (Network Quality Analysis) is a network testing tool that allows connectivity testing between two devices.

Configuring NQA between PE1 and PE2 will verify end-to-end reachability.

Option B: " On PE1 and PE2, checking whether the ARP table contains the ARP entry of the peer network segment. "

❌ Incorrect.

ARP (Address Resolution Protocol) is only used for resolving MAC addresses within the same broadcast domain.

Since PE1 and PE2 are in different network segments (separated by a routed network), they will not have ARP entries for each other.

Instead, routing entries should be checked, not ARP.

Option C: " On PE1, using 192.168.1.1 as the source address to ping 192.168.2.1. "

✅ Correct.

A simple ping test using the source address of PE1 (192.168.1.1) to reach PE2 (192.168.2.1) will verify whether routing between the two locations is functional.

Option D: " On PE1 and PE2, checking whether there are routes to each other’s network segment in the routing tables. "

✅ Correct.

If routing is not configured correctly, PE1 and PE2 will not know how to reach each other.

Checking the routing table ensures that both PEs have the correct next-hop information.

Final Answer:

✅ A, C, and D are correct.

HCIP-Datacom-Advanced Routing & Switching Technology References:

Using NQA for Network Connectivity Testing

Verifying Routing Table Entries for Inter-Network Communication

Understanding ARP and Its Limitations in Routed Networks