Huawei HCIP-Datacom-Advanced Routing & Switching Technology V1.0 H12-831_V1.0 Exam Practice Test

Answer : B, D

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

Answer : C

Comprehensive and Detailed In-Depth

Understanding the IS-IS Network Structure in the Questio n :

IS-IS Area IDs and Router Roles

Area 49.0001 (Level-1-2): Contains R1, R2, R4 (all Level-1-2 routers).

Area 49.0002 (Level-1-2 & Level-1): Contains R3 (Level-1-2) and R5 (Level-1 only).

Key Command Used: ipv6 default-route-advertise always level-1

This command forces R4 to advertise a default route (::/0) to all Level-1 routers within its area.

Only Level-1 routers in the same area as R4 will receive the default route.

Level-2 routers do not receive or propagate this default route unless additional configuration is done.

Route Distribution Analysis:

R4 (Level-1-2) is configured to advertise a default route to Level-1 routers.

R1 and R2 (both Level-1-2) are in the same area (49.0001) as R4, so they receive the default route.

R3 (Level-1-2) is in area 49.0002 but connects to R4 (49.0001), meaning it can receive the default route through its Level-1 connection.

R5 (Level-1 only) is in area 49.0002, but R4 does not propagate the default route to another Level-1 area (49.0002).

Since R5 is a Level-1 router and does not have a Level-2 connection, it cannot receive the default route from R4.

Final Conclusion:

R1 receives the default route.

R2 receives the default route.

R3 receives the default route.

R5 does NOT receive the default route.

Thus, the correct answer is: C. R5.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 -- IS-IS Multi-Topology and IPv6 Routing

Huawei Official HCIP-Datacom Study Guide -- IS-IS Default Route Advertisement for Level-1 and Level-2 Areas

Huawei Documentation on ipv6 default-route-advertise always level-1 Command Behavior

Answer : A

Answer : B

Comprehensive and Detailed In-Depth

To verify the correct answer, we need to analyze Bidirectional Forwarding Detection (BFD) behavior and the provided configuration.

1. Understanding BFD Configuration Parameters

BFD (Bidirectional Forwarding Detection) is a protocol used for fast failure detection between directly connected devices.

Key Configuration Parameters in BFD:

Peer IP (bind peer-ip)

This specifies the destination router's IP address for the BFD session.

Correctly configured on both R1 and R2.

Discriminator Local/Remote (discriminator local X / remote Y)

These values must match between the two routers.

Correctly configured (R1: local 1, remote 2; R2: local 2, remote 1).

Min-TX Interval (min-tx-interval)

Defines the minimum transmit interval for BFD packets.

Missing from R2's configuration (could be a cause for mismatch).

Min-RX Interval (min-rx-interval)

Defines the minimum receive interval for BFD packets.

Missing from R2's configuration (could be a cause for mismatch).

2. Analyzing the Configuration on R1 and R2

Configuration on R1 (Correct)

shell

CopyEdit

bfd tor2 bind peer-ip 10.0.12.2

discriminator local 1

discriminator remote 2

min-tx-interval 1500

min-rx-interval 1500

This configuration is correct.

Configuration on R2 (Incomplete)

shell

CopyEdit

bfd tor1 bind peer-ip 10.0.12.1

discriminator local 2

discriminator remote 1

Missing min-tx-interval and min-rx-interval.

3. Why the Answer is FALSE?

A BFD session does NOT go down due to mismatched timing parameters.

BFD dynamically negotiates timing values, meaning even if R2 is missing min-tx/min-rx values, the session should still establish.

However, the session will fail if the peer IP or discriminator values are incorrect (which they are NOT in this case).

The actual cause of failure in this case is likely the missing min-tx and min-rx settings on R2, NOT a mismatch between R1 and R2.

Answer : B

Comprehensive and Detailed In-Depth

Step 1: Analyzing the Primary Path

The given network uses IS-IS Auto FRR, which ensures a backup route in case of failure.

The shortest path from R1 to 10.0.3.3/32 is calculated based on the OSPF link costs:

Path 1 (Primary Path): R1 R2 R3

Cost: 10 (R1R2) + 5 (R2R3) = 15

Step 2: Checking the Backup Path

The statement claims that the backup path is R1 R4 R2 R3. Let's calculate the cost:

Path 2 (Backup Path via R4): R1 R4 R2 R3

Cost: 10 (R1R4) + 50 (R4R2) + 5 (R2R3) = 65 (Too high)

The backup path should be an alternative shortest path that is as close as possible to the primary path in cost.

R1 R4 R2 R3 is not a feasible backup path because the cost (65) is significantly higher than the primary path (15).

Step 3: Correct Backup Path Selection

If IS-IS Auto FRR is enabled, a feasible backup path should have a cost close to the primary path.

In this scenario, no viable alternative path meets the Auto FRR requirements efficiently.

The given backup path is incorrect.

Final Answer: FALSE (Option B)

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 -- IS-IS Auto FRR Mechanism

OSPF Route Selection and Fast Reroute Principles

OSPF and IS-IS Path Cost Calculation

Answer : A, B, D

Comprehensive and Detailed In-Depth

Understanding the OSPF Network Structure in the Questio n :

OSPF Areas & Routers:

Area 3: Contains R5 (which has loopback 10.0.5.5/32).

Area 1: Contains R6.

Area 2: Contains R4.

Area 0 (Backbone Area): Contains R1, R2, and R3 (which interconnect the other areas).

ACL 2000 Filtering Rule:

The ACL rule 2000 explicitly denies 10.0.5.5/32 from being imported.

The filter 2000 import command applies this filter to Area 0, preventing routes from Area 3 (including R5's loopback) from being learned by Area 0 routers (R1, R2, and R3).

Route Distribution Analysis:

R5 (Area 3):

R5 has 10.0.5.5/32 configured on its Loopback0.

Since OSPF is enabled, R5 advertises the route to R6 in Area 1.

R6 (Area 1) R2 (Area 0, Backbone Router):

Without filtering, R6 would normally propagate 10.0.5.5/32 to R2 (since R2 is a backbone router in Area 0).

However, since ACL 2000 is applied in Area 0, R2 blocks this route from being imported.

Therefore, R2 does not learn 10.0.5.5/32.

R2 R1 and R3 (Both in Area 0):

R2 would typically share any learned routes with R1 and R3 in Area 0.

But since R2 itself does not have 10.0.5.5/32, neither R1 nor R3 can receive it.

Thus, R1 and R3 also do not have 10.0.5.5/32 in their routing tables.

R4 (Area 2) is Unaffected:

Since R4 is in Area 2, it is not directly impacted by the filter applied in Area 0.

It can still receive the route via another path if redistribution is configured properly.

Final Conclusion:

R1, R2, and R3 do not have the 10.0.5.5/32 route due to the filter 2000 import command applied in Area 0.

R4 may still have the route since it is not affected by the filtering in Area 0.

Thus, the correct answer is:

R1, R3, R2 do not have the route 10.0.5.5/32 in their routing tables.

HCIP-Datacom-Advanced Routing & Switching Technology V1.0 -- OSPF Route Filtering Mechanisms

Huawei Official HCIP-Datacom Study Guide -- OSPF Inter-Area Route Advertisement and Filtering

Huawei Documentation on filter import and ACL-based OSPF route filtering

Answer : C

Comprehensive and Detailed In-Depth

Multicast MAC addresses follow the format 01-00-5E-XX-XX-XX, derived from the IPv4 multicast address (224.0.0.0 -- 239.255.255.255).

The lower 23 bits of the IPv4 multicast address are mapped to the MAC address, causing ambiguity because different IPv4 multicast addresses can share the same MAC address.

The IPv4 multicast range (224.0.0.0 -- 239.255.255.255) is divided as follows:

224.0.0.0 -- 224.0.0.255: Local Network Control Block (e.g., 224.0.0.1)

224.0.1.0 -- 238.255.255.255: Global and Reserved Multicast (e.g., 224.0.1.1, 225.0.1.1)

239.0.0.0 -- 239.255.255.255: Private Multicast (Not mapped to 01-00-5E)

The MAC 01-00-5e-00-01-01 corresponds to an IPv4 multicast address in the range 224.0.0.0 -- 238.255.255.255, but not to 239.128.1.1, because addresses in the 239.x.x.x range are private multicast addresses.

Reference: HCIP-Datacom Advanced Routing & Switching Technology -- Multicast MAC Address Mapping