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

1. Understanding VLAN Aggregation in Huawei Switches

VLAN aggregation is a technique that groups multiple VLANs (sub-VLANs) under a single Super-VLAN.

Super-VLANs do not have member interfaces but include multiple Sub-VLANs that share a common gateway (VLANIF interface).

2. Inter-Sub-VLAN Communication Requirement

By default, hosts in different sub-VLANs cannot communicate directly.

To enable communication between different sub-VLANs within the same Super-VLAN, an inter-sub-VLAN proxy must be enabled.

This is done using the inter-sub-vlan-proxy enable command in the VLANIF interface of the Super-VLAN.

3. Correct Command Usage

The command format is:

shell

CopyEdit

supervlan inter-sub-vlan-proxy enable

This command must be executed under VLANIF 10, corresponding to the Super-VLAN.

4. Why is the Answer " supervlan " ?

The missing parameter in the command should be supervlan, because it is used to enable communication between Sub-VLANs under a Super-VLAN.

This is a specific Huawei command used in HCIP-Datacom-Advanced Routing & Switching Technology certification.

Comprehensive and Detailed In-Depth Explanation:

1. Understanding MPLS Label Forwarding Information

The output of the display mpls lsp command shows the Label Forwarding Information Base (LFIB) used by the router to forward MPLS packets.

Each entry consists of:

FEC (Forwarding Equivalence Class): The destination IP prefix.

In Label / Out Label: Incoming label (received) and outgoing label (sent).

In IF / Out IF: Incoming and outgoing interfaces.

2. Analyzing the Given LSP Table

FEC (Destination IP)

In Label

Out Label

Outgoing Interface

1.1.1.1/32

3

NULL

-

2.2.2.2/32

NULL

3

GE0/0/1

2.2.2.2/32

1026

3

GE0/0/1

3.3.3.3/32

NULL

1027

GE0/0/1

3.3.3.3/32

1027

1027

GE0/0/1

Key Observations:

NULL means the label is removed (Penultimate Hop Popping - PHP).

Label 3 is the implicit null label, meaning the label is removed before sending to the next router.

For destination 3.3.3.3, the router adds label 1027 before forwarding it to GE0/0/1.

3. Evaluating Each Answer Option

Option A: " Before forwarding a packet destined for 2.2.2.2, the device adds label 3 to the packet. " → Incorrect.

The output shows that packets destined for 2.2.2.2 have the NULL (label 3) entry, which means the label is removed before forwarding, not added.

Option B: " Before forwarding a packet destined for 1.1.1.1, the device adds label 3 to the packet. " → Incorrect.

The entry 1.1.1.1 → 3/NULL means the label is removed (PHP), so the device does not add label 3.

Option C: " Before forwarding a packet destined for any IP address, the device removes labels from the packet. " → Incorrect.

The device removes labels only for some destinations (e.g., 1.1.1.1 and 2.2.2.2), but it adds label 1027 for 3.3.3.3.

Not all IPs have their labels removed.

Option D: " Before forwarding a packet destined for 3.3.3.3, the device adds label 1027 to the packet. " → Correct.

The entry 3.3.3.3 → NULL/1027 means that the router adds label 1027 before forwarding packets to GE0/0/1.

Final Answer:

Answer: D (Before forwarding a packet destined for 3.3.3.3, the device adds label 1027 to the packet).

HCIP-Datacom-Advanced Routing & Switching Technology References:

Understanding MPLS LDP (Label Distribution Protocol) and LFIB

Implicit Null (Label 3) and Penultimate Hop Popping (PHP)

MPLS Label Swapping and Forwarding Process

Comprehensive and Detailed In-Depth Explanation:

To determine which devices perform MPLS label operations, we need to analyze MPLS forwarding behavior based on the roles of each router in the MPLS domain.

1. Understanding MPLS Label Operations

MPLS label switching involves three main operations:

Label Push (Ingress LSR - Label Imposition): The ingress router (R1) assigns an MPLS label to the packet.

Label Swap (Transit LSR - Label Forwarding): The transit routers (R2, R3) swap the label for the next-hop router.

Label Pop (Egress LSR - Label Disposition): The egress router (R4) removes the MPLS label before forwarding the packet to its final destination.

2. Examining MPLS Roles of Each Router

???? R1 (Ingress LSR) → Performs Label PUSH

R1 adds an MPLS label (1025) to the IP packet and forwards it to R2.

Operation: Push MPLS Label (Label Imposition).

✅ R1 performs MPLS label operations.

???? R2 (Transit LSR) → Performs Label SWAP

R2 receives a labeled packet (1025) from R1, swaps it with label 1026, and forwards it to R3.

Operation: Swap MPLS Label (Transit Label Forwarding).

✅ R2 performs MPLS label operations.

???? R3 (Transit LSR) → Performs Label SWAP

R3 receives label 1026 and swaps it with label 3, then forwards it to R4.

Operation: Swap MPLS Label (Transit Label Forwarding).

✅ R3 performs MPLS label operations.

???? R4 (Egress LSR) → Does NOT Perform MPLS Operations

R4 is the egress router and does not forward the packet further using MPLS.

The last router removes the MPLS label (Pop) and forwards the plain IP packet.

R4 is NOT performing MPLS label switching (swap or push), only popping the label before delivering the packet.

❌ R4 does NOT perform MPLS label operations.

Comprehensive and Detailed In-Depth Explanation:

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 Answer: 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.

???? Area Overview from Diagram:

Area 1 (Green) – Stub area

Area 2 (Red) – Common (standard) area

Area 3 (Blue) – NSSA

R5 in Area 3 (NSSA) is redistributing static IPv6 route 2000::5/128 using import-route.

???? Option A: R1 generates an AS-External-LSA.

❌ False

R1 is in Area 1, a stub area.

AS-External-LSAs (Type-5) are not allowed in stub areas.

So R1 cannot generate Type-5 LSAs, nor can it forward them into Area 1.

???? Option B: R3 generates an AS-External-LSA.

✅ True

Area 3 is an NSSA, and R5 redistributes a route (2000::5/128) via import-route.

In NSSA, redistributed routes are advertised using Type-7 LSAs.

R3, acting as the ABR for Area 3, translates Type-7 to Type-5 LSAs (AS-External-LSA) and floods them into Area 0.

Therefore, R3 generates the AS-External-LSA.

???? Option C: R2 generates an Inter-Area-Router-LSA in area 0.

✅ True

R2 connects Area 0 and Area 2.

It must advertise its area 2 prefixes into area 0, and it does so using Type-3 Inter-Area-Prefix-LSA and Type-4 Inter-Area-Router-LSA.

Type-4 LSA carries ASBR information, which R2 must advertise into Area 0.

???? Option D: R2 generates an Inter-Area-Router-LSA in area 2.

❌ False

Inter-Area-Router-LSA (Type-4) is used only to describe an ASBR in another area.

R2 would not generate Type-4 LSAs into its own attached area (Area 2).

It injects Type-4 into other areas (like Area 0), not into Area 2.

✅ Final Answer: B, C

Official Huawei Extract:

" In OSPFv3, Type-5 LSAs (AS-External) are not allowed in stub areas and NSSAs. In an NSSA, redistributed routes are advertised as Type-7 LSAs. These are translated into Type-5 LSAs by the ABR for flooding into the backbone area. Inter-Area-Router-LSAs (Type-4) are used to inform other areas about ASBRs. "

— [Huawei HCIA-Datacom Certification Guide – OSPFv3 LSA Types and Area Roles Chapter]