Pass the Huawei HCIP-Datacom H12-831_V1.0 Questions and answers with CertsForce

Comprehensive and Detailed In-Depth Explanation:

Understanding the LSA Table in the Figure

The LSA Type displayed in the LSDB of R3 is an Intra-Area-Prefix-LSA (Type 9), with the following attributes:

LS Type: Intra-Area-Prefix-LSA (Type 9)

Link State ID: 0.0.0.1

Originating Router: 10.0.2.2 (R2)

Referenced LSA Type: 0x2001 (Router-LSA, Type 1)

Referenced Link State ID: 0.0.0.0

Referenced Originating Router: 10.0.2.2 (R2)

Prefix: 2000:2::/128

Analysis of the Statement

What is an Intra-Area-Prefix-LSA (Type 9)?

Used in OSPFv3 to advertise IPv6 prefixes associated with a Router-LSA (Type 1) or Network-LSA (Type 2).

Each router generates its own Router-LSA (Type 1) and references it in an Intra-Area-Prefix-LSA (Type 9).

How does this apply to R3's LSDB?

The LSA is generated by R2 (10.0.2.2), meaning R2 originated the prefix advertisement.

The referenced LSA is a Router-LSA, indicating that the IPv6 prefix is associated with R2's router advertisement.

Since R3 sees this LSA in its LSDB, it means R2 has advertised its IPv6 prefix (2000:2::/128) into the OSPFv3 domain.

✅ Since the LSA describes an IPv6 prefix associated with R2’s Router-LSA, the statement is TRUE.

Final Conclusion:

✅ The LSA is generated by R2 and describes the IPv6 prefix associated with the Router-LSA.✅ Thus, the correct answer is: A. TRUE.

Comprehensive and Detailed In-Depth Explanation:

To verify the correct answers, let's analyze how BGP/MPLS IP VPN is used for secure communication and isolation in an enterprise network.

1. Understanding BGP/MPLS IP VPN Concepts

MPLS VPN (Multiprotocol Label Switching Virtual Private Network) is used to:

Allow communication between specific sites by using Route Targets (RTs).

Ensure isolation of specific areas (e.g., R&D vs. non-R&D) by controlling RT import/export policies.

Utilize Route Distinguisher (RD) to make overlapping IP addresses unique within the VPN.

2. Analyzing the Answer Choices

✅ A. "To enable communication between the headquarters and branch R&D areas, both the ERT and IRT of VPN1 and VPN2 can be set to 100:100." → TRUE

Explanation:

ERT (Export Route Target) and IRT (Import Route Target) define which VPNs share routing information.

If VPN1 (HQ R&D) and VPN2 (Branch R&D) use the same RT (100:100), they will exchange routes, enabling communication.

Correct configuration:

VPN1: ERT 100:100, IRT 100:100

VPN2: ERT 100:100, IRT 100:100

✅ This is correct and enables communication between HQ and branch R&D areas.

❌ B. "To implement communication between the headquarters and branch R&D areas, the RDs of VPN1 and VPN2 need to be set to the same value." → FALSE

Explanation:

RD (Route Distinguisher) is only used to make overlapping IP addresses unique within the MPLS VPN.

RD does NOT control route exchange between VPNs (RTs control route exchange).

VPN1 and VPN2 can have different RDs but still communicate if they share the same RT (100:100).

✅ RDs do NOT need to be the same for VPNs to communicate.

❌ This statement is false.

❌ C. "R&D areas and non-R&D areas have overlapping address spaces. Therefore, services in the two areas cannot be isolated." → FALSE

Explanation:

Overlapping address spaces are common in MPLS VPNs and can be isolated using unique Route Targets (RTs).

As long as VPNs have different RTs, their traffic remains isolated.

For example:

VPN1 (R&D): RT 100:100

VPN3 (non-R&D): RT 200:200

Even with overlapping IPs, R&D and non-R&D areas are completely isolated.

❌ This statement is false.

✅ D. "To isolate R&D areas from non-R&D areas at the headquarters, the RTs of VPN1 can all be set to 100:100 and the RTs of VPN3 can all be set to 200:200." → TRUE

Explanation:

Setting different RTs for R&D (100:100) and non-R&D (200:200) ensures complete isolation.

Correct configuration:

VPN1 (R&D): RT 100:100

VPN3 (non-R&D): RT 200:200

Since VPN1 and VPN3 do NOT share the same RTs, their routes remain separate.

✅ This ensures isolation between R&D and non-R&D areas.

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.

Comprehensive and Detailed In-Depth Explanation:

Understanding Intra-Area-Prefix-LSA (Type 9) in OSPFv3

OSPFv3 uses the Intra-Area-Prefix-LSA (Type 9) to advertise IPv6 prefixes associated with either:

A Router-LSA (Type 1) → Describes links and interfaces.

A Network-LSA (Type 2) → Advertises multi-access networks (if a Designated Router exists).

Each router generates one Intra-Area-Prefix-LSA to advertise its own IPv6 prefixes.

Prefix Analysis for Each Router

R1's IPv6 Prefixes:

2000:12::1/64

2001:12::1/64

2002:12::1/64

2003:12::/64 (Shared link with R2)

Total Prefixes in R1’s Intra-Area-Prefix-LSA = 4

✅ R1 advertises four prefixes in its Intra-Area-Prefix-LSA.

R2's IPv6 Prefixes:

2003:12::2/64 (Shared link with R1)

Total Prefixes in R2’s Intra-Area-Prefix-LSA = 1

✅ R2 advertises only one prefix in its Intra-Area-Prefix-LSA.

Checking Each Option:

✅ A. The Intra-Area-Prefix-LSA generated by R2 describes three prefixes. (❌ False, R2 only has one prefix).

✅ B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes. (✔ True, R1 has four prefixes).

✅ C. The Intra-Area-Prefix-LSA generated by R2 describes four prefixes. (❌ False, R2 only has one prefix).

✅ D. The Intra-Area-Prefix-LSA generated by R1 describes three prefixes. (❌ False, R1 has four prefixes).

Final Conclusion:

✅ B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes.

Thus, the correct answer is: B. The Intra-Area-Prefix-LSA generated by R1 describes four prefixes.