H12-891_V1.0 Exam Dumps - HCIE-Datacom V1.0

Comprehensive and Detailed Explanation:

✔ All four egress modes are supported in Huawei CloudCampus Virtualized Fabric to provide flexibility in connecting external networks.

✔ Modes Explained:✅ Layer 3 Shared Egress → Multiple VNs share a single Layer 3 gateway for external communication.✅ Layer 2 Shared Egress → Multiple VNs share the same Layer 2 link to the external network.✅ Layer 3 Exclusive Egress → Each VN has its own separate Layer 3 gateway to external networks.✅ Layer 2 Exclusive Egress → Each VN has its own dedicated Layer 2 link for external connectivity.

📖 Reference: Huawei HCIE Datacom – CloudCampus Fabric Egress Modes

Understanding Prefix Lists

IP Prefix-Lists are used for filtering BGP routes and controlling route advertisement & redistribution.

The command ip ip-prefix TEST permit 10.0.0.0 24 less-equal 30 means:

Matches prefix 10.0.0.0/24 exactly.

Matches any subnet of 10.0.0.0/24 with a prefix length between 24 and 30.

Analysis of Routes:

✅ 10.0.0.0/24 → Matches exactly.

✅ 10.0.0.1/30 → Falls within 10.0.0.0/24 & length ≤30.

❌ 10.0.1.0/24 → Not within 10.0.0.0/24 range.

❌ 10.0.2.0/24 → Not within 10.0.0.0/24 range.

Real-World Use Case:

BGP route filtering: Only allows 10.0.0.0/24 and its subnets (up to /30).

Prevents unintended route propagation in large-scale networks.

✅ Reference: Huawei HCIE-Datacom Guide – BGP Prefix-Lists

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Understanding the Routing Table Entries on R4

0.0.0.0/0 (Default Route) is installed twice in the routing table.

The NextHop values for the default route:

10.1.24.1 (GigabitEthernet0/0/1)

10.1.34.1 (GigabitEthernet0/0/0)

Cost: Both routes have a metric (Cost) of 10, meaning they are equal-cost routes.

Protocol: ISIS-L1 (Intermediate System to Intermediate System - Level 1) confirms these routes are coming from IS-IS routing.

Flags: D (Dynamic) means these routes were dynamically learned via IS-IS.

Why is Option D Correct?

Since both routes have the same cost (10), they are considered equal-cost default routes.

The router will use both routes in a load-sharing fashion.

The answer is NOT A (Four equal-cost routes) because there are only two default routes, not four.

The answer is NOT B (One default route) because there are two default routes in the table.

The answer is NOT C (Two default routes with different costs) because both routes have the same cost (10).

Real-World Application

Equal-Cost Multi-Path (ECMP): The router can perform load balancing across the two equal-cost paths.

Resilience & Redundancy: If one link fails, the other can take over without re-calculating the entire routing table.

✅ Reference: Huawei HCIE-Datacom Study Guide – IS-IS Routing & ECMP Load Balancing

Comprehensive and Detailed Explanation:

OSPFv2 (for IPv4) and OSPFv3 (for IPv6) LSAs differ in function and naming conventions.

Key Differences in OSPFv3 LSAs:

OSPFv3 does not use ASBR-Summary-LSA. Instead, it introduces new Inter-Area Prefix LSAs (Type 3) and Inter-Area Router LSAs (Type 4).

OSPFv2 ASBR-Summary-LSA (Type 4) is replaced in OSPFv3 by Inter-Area Router LSA (Type 4).

OSPFv3 LSA Types:

✔ Router-LSA (Type 1) – Describes router interfaces and links.✔ Network-LSA (Type 2) – Describes broadcast network links.✔ Inter-Area Prefix LSA (Type 3) – Replaces Summary LSAs for routes.✔ Inter-Area Router LSA (Type 4) – Replaces ASBR Summary LSAs.✔ AS-External LSA (Type 5) – Describes external routes (same as OSPFv2).

Since ASBR-Summary-LSA (Type 4) does not exist in OSPFv3, the correct answer is A.

📖 Reference: Huawei HCIE Datacom – OSPFv3 LSA Types

Understanding Huawei SD-WAN Tunneling Technologies

Huawei SD-WAN uses secure tunneling to connect branches, data centers, and cloud services.

🔹 Tunneling Technologies in SD-WAN:✅ IPsec (Answer B) → Provides secure encrypted tunnels over public or private networks.✅ GRE over IPsec (Answer D) → Encapsulates traffic inside GRE, then encrypts with IPsec, enabling support for multicast and non-IP traffic.

❌ A. WLAN (Incorrect Choice) → WLAN is a wireless technology, not a tunneling protocol.❌ C. MPLS (Incorrect Choice) → MPLS is a core network transport technology but is not used to establish SD-WAN data channels directly.

Why are Answers B and D Correct?

✅ Huawei SD-WAN primarily uses IPsec for data encryption.✅ GRE over IPsec is used when supporting multicast or dynamic routing protocols over tunnels.

✅ Reference: Huawei HCIE-Datacom Guide – SD-WAN Tunneling Mechanisms

Understanding OSPF Multi-Area Routing

🔹 OSPF (Open Shortest Path First) is a link-state routing protocol that uses a hierarchical area design for scalability.🔹 OSPF Areas in the Diagram:

Area 0 (Backbone Area): Contains R4 (Loopback 10.0.4.4/32).

Area 1: Contains R1 (Loopback 10.0.1.1/32) and R2 (Loopback 10.0.2.2/32).

Area 2: Contains R3 (Loopback 10.0.3.3/32) and R5 (Loopback 10.0.5.5/32).

R1 and R2 connect Area 1 to Area 0.

R1 and R3 connect Area 1 to Area 2.

How OSPF Advertises Routes Across Areas

✅ Intra-area communication (within the same area) is always possible.✅ Inter-area communication is possible if the ABR (Area Border Router) correctly advertises routes.✅ OSPF does NOT automatically advertise routes from one non-backbone area (e.g., Area 2) to another (e.g., Area 0) unless explicitly allowed.

Analysis of the Answer Choices:

❌ A. 10.0.3.3 and 10.0.5.5 (Incorrect)

Both R3 (10.0.3.3) and R5 (10.0.5.5) are in Area 2.

R3 and R5 can communicate directly, but OSPF rules require an Area Border Router (ABR) to share routing information between areas.

Since no information is provided about inter-area route redistribution, we cannot confirm that R3 and R5 can reach each other.

❌ B. 10.0.2.2 and 10.0.5.5 (Incorrect)

R2 (10.0.2.2) is in Area 1, and R5 (10.0.5.5) is in Area 2.

R2 does NOT have direct OSPF reachability into Area 2.

✅ C. 10.0.2.2 and 10.0.3.3 (Correct)

R2 (10.0.2.2) is in Area 1, and R3 (10.0.3.3) is in Area 2.

R1 connects both Area 1 and Area 2, meaning R2 and R3 can communicate via R1.

R1 is the ABR (Area Border Router) between Area 1 and Area 2, so it will advertise routes from R3 to R2 and vice versa.

❌ D. 10.0.4.4 and 10.0.2.2 (Incorrect)

R4 (10.0.4.4) is in Area 0 (Backbone), and R2 (10.0.2.2) is in Area 1.

R2 does NOT connect directly to Area 0, so R2 does not learn routes from Area 0 unless R1 explicitly redistributes them.

No explicit information about route redistribution is provided.

Final Answer: C (10.0.2.2 and 10.0.3.3)

✅ Reference: Huawei HCIE-Datacom Guide – OSPF Multi-Area Routing & ABR Role

Real-World Application:

Enterprise WAN Networks: Multi-area OSPF is used to scale large enterprise networks while maintaining fast convergence.

Service Provider Networks: ABRs control route distribution, preventing unnecessary flooding of routing updates across areas.

Analyzing the Routing Table Output:

The command display ipv6 routing-table protocol isis shows all IPv6 routes learned via IS-IS.

The output shows "Summary Count: 6", meaning R1 has six IS-IS IPv6 routes.

Explanation of Correct Answers:✅ A. R1 has six IS-IS IPv6 routes.

The "Summary Count: 6" confirms that six IS-IS IPv6 routes exist in R1's routing table.

✅ C. IS-IS IPv6 must have been enabled on GigabitEthernet0/0/1 of R1.

The interface GigabitEthernet0/0/1 is listed as the next-hop, meaning IS-IS IPv6 must be enabled on that interface.

✅ D. R1 is not a Level-1 device.

The protocol is listed as "ISIS-L2", indicating that R1 is an IS-IS Level-2 (backbone) router, not a Level-1 router.

Incorrect Answer Explanation:❌ B. R1 does not have IS-IS IPv6 routes.

Wrong! The output clearly shows six IS-IS IPv6 routes, proving this statement false.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IPv6 Routing Protocols Guide – IS-IS for IPv6

HCIE-Datacom Routing & Switching Training – IS-IS L1 & L2 Operations

Huawei IS-IS Configuration Guide – IPv6 Route Management

Comprehensive and Detailed Explanation:

Ethernet VPN (EVPN) is an advanced L2VPN technology that enhances MAC learning and forwarding in data center and enterprise networks. Different EVPN route types are used for various functions:

Ethernet A-D (Auto-Discovery) Route: Used for auto-discovery of PE devices and does carry labels.

MAC/IP Advertisement Route: Distributes MAC-to-IP mappings and carries labels for forwarding decisions.

Ethernet Segment Route: Does not carry MPLS labels as it is used to signal multi-homing and redundancy information.

Inclusive Multicast Route: Used for multicast forwarding and carries labels for tunnel identification.

Since Ethernet Segment Route is used only for multi-homing signaling and does not carry MPLS labels, the correct answer is C.

📖 Reference: Huawei HCIE Datacom Study Guide - EVPN Route Types