Huawei H12-831_V1.0 Exam Dumps

Comprehensive and Detailed In-Depth

To verify the correct answer, let's analyze the LSA types in OSPFv3 and how they work in the given topology.

1. Understanding OSPFv3 LSAs in the Figure

From the command output shown in the image:

LS Type: Intra-Area-Prefix-LSA (Type 9 in OSPFv3).

Originating Router: 10.0.2.2 (R2).

Referenced LS Type: 0x2002, which corresponds to a Network-LSA (Type 2).

Prefix Advertised: 2000:23::/64, which is an IPv6 prefix associated with a network segment.

2. What is an Intra-Area-Prefix LSA (Type 9) in OSPFv3?

In OSPFv3, Type 9 LSAs (Intra-Area-Prefix LSAs) describe IPv6 prefixes associated with either Router-LSAs (Type 1) or Network-LSAs (Type 2).

In multi-access networks (e.g., Ethernet), the DR (Designated Router) generates a Network-LSA (Type 2), which represents the shared network segment.

R2 is likely the DR in this topology, meaning it generates a Network-LSA (Type 2) and an associated Intra-Area-Prefix LSA (Type 9) for the subnet.

3. Analyzing Why the Statement is TRUE

R2 (10.0.2.2) is the originator of the Intra-Area-Prefix LSA (Type 9).

The LSA references a Network-LSA (Type 2), confirming that R2 is the DR for the subnet.

This means the LSA is correctly describing the IPv6 prefix associated with the network.

Since the LSA is visible in R3's LSDB, R3 is learning this information from R2.

All these points confirm that the statement is TRUE.

Comprehensive and Detailed In-Depth

1. Understanding the MPLS Data Flow in the Figure

PC1 (1.1.1.1) sends a ping to PC2 (3.3.3.3).

The MPLS domain includes R1, R2, and R3.

R1 pushes an MPLS label onto the packet (Label: 300).

Packets from PC1 to PC2 are label-switched (MPLS forwarding).

Packets from PC2 to PC1 do not carry an MPLS label (IP forwarding).

2. Evaluating Each Answer Option

Option A: 'If the device is R3, R3 forwards the packet from PC1 to PC2 over an IP route.'

Incorrect.

The packet carries an MPLS label (Label 300) when entering the MPLS domain.

This means that R3 forwards the packet using MPLS, not a standard IP route.

If R3 were using an IP route, there would be no MPLS label in the packet.

Option B: 'Packets from PC1 to PC2 are forwarded based on MPLS labels in the MPLS domain.'

Correct.

The packet capture shows an MPLS label (Label 300), proving that PC1's traffic is being forwarded using MPLS switching inside the MPLS domain.

This confirms that MPLS is being used for forwarding in one direction (PC1 PC2).

Option C: 'Packets from PC2 to PC1 are forwarded based on the IP packet header in the MPLS domain.'

Correct in concept but incorrect in context.

The packet capture shows that the return traffic (PC2 PC1) does not have an MPLS label.

However, the phrase 'in the MPLS domain' makes this statement misleading, as R3 is forwarding based on pure IP routing, not MPLS forwarding.

Option D: 'PC1 pings PC2.'

Correct.

The packet capture clearly shows ICMP Echo Request (ping) from PC1 (1.1.1.1) to PC2 (3.3.3.3) and an ICMP Echo Reply from PC2.

This confirms that PC1 is pinging PC2 successfully.

Final Answer:

B and D are correct.

HCIP-Datacom-Advanced Routing & Switching Technology Reference:

MPLS Label Forwarding and Static LSPs

MPLS vs. IP Routing in Different Traffic Flows

Packet Header Analysis in MPLS Networks

Comprehensive and Detailed In-Depth

1. Understanding Site of Origin (SoO) in MPLS VPNs

SoO (Site of Origin) is used in MPLS VPNs to prevent loops in multi-homed CE scenarios.

Routes with the same SoO value are not advertised back to the same site.

2. Analysis of Each Answer Choice

A . 'To enable CE3 to receive the route, run the command peer 10.1.1.1 soo 200:1 on PE1.' ( False)

SoO is used to prevent loops by tagging routes that belong to the same site.

Applying SoO (200:1) on PE1 for CE1 means that any other PE (such as PE2) receiving the route will not advertise it back to the same site (CE1).

This statement is false because applying SoO here does not directly enable CE3 to receive the route. Instead, CE3 must accept routes with SoO values properly configured.

B . 'If the commands peer 10.1.1.1 soo 200:1 and peer 10.1.2.1 soo 200:1 are run on PE1, CE2 accepts the route.' ( False)

SoO ensures that a route received from one CE is not sent back to another CE in the same site.

If SoO (200:1) is assigned to CE1 and CE2, routes will be blocked because they share the same SoO tag.

Thus, CE2 will not accept the route, making this statement false.

C . 'If the command peer 10.1.3.1 substitute-as is run on PE2, CE3 accepts the route.' ( True)

substitute-as allows a router to replace the received AS number in the AS_PATH with another AS number, ensuring that routes are accepted even when AS_PATH filtering is in place.

This prevents CE3 from rejecting the route due to AS-Path loop prevention.

Thus, this statement is true.

D . 'If no additional action is taken, CE3 discards the route.' ( True)

By default, CE3 will discard the route because of BGP loop prevention (same AS in the AS_PATH).

To allow CE3 to receive the route, the allowas-in or substitute-as command must be configured on PE2.

Thus, this statement is true.

3. Evaluating the Answer Choices

Option

Correct?

Reasoning

A

False

Applying SoO does not directly enable CE3 to receive the route.

B

False

If both CE1 and CE2 have the same SoO value, CE2 will reject the route.

C

True

Substitute-AS allows CE3 to accept the route by modifying the AS-Path.

D

True

Without additional configuration, CE3 will discard the route due to AS-Path loop prevention.

Correct Answe r : A and B are false.

Final Conclusion:

SoO prevents routing loops in MPLS VPN multi-homing.

CE2 will reject the route if it has the same SoO as CE1.

CE3 requires the substitute-as or allowas-in command to accept the route.

Thus, statements A and B are false.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 -- BGP SoO and AS-Path Loop Prevention

Huawei Official HCIP-Datacom Study Guide -- MPLS VPN Route Control

Huawei Documentation on BGP SoO and AS_PATH Filtering

Comprehensive and Detailed In-Depth

OSPFv3 (for IPv6) packets are directly encapsulated in IPv6 without using UDP or TCP.

The Next Header field in IPv6 is similar to the Protocol field in IPv4, indicating the protocol type of the payload.

IANA (Internet Assigned Numbers Authority) has assigned protocol number 89 to OSPF.

OSPFv3 packets always use Next Header value = 89 inside IPv6 headers.

Reference: HCIP-Datacom Advanced Routing & Switching Technology -- OSPFv3 Packet Encapsulation