Network Slicing Using Channelized Sub-Interfaces and FlexE

Both channelized sub-interfaces and FlexE (Flexible Ethernet) are used for network slicing, but they have different application scenarios:

✅ A. Channelized sub-interface is recommended for interfaces with bandwidth < 50 Gbit/s.

Channelized sub-interfaces split a physical interface into multiple logical sub-interfaces.

Best for lower-bandwidth links (<50 Gbit/s).

✅ B. FlexE is recommended for 50GE and higher-rate interfaces.

FlexE divides a high-bandwidth physical link (e.g., 100GE, 400GE) into multiple virtual slices.

Used in high-speed backbone and data center networks.

✅ C. Only FlexE-based network slicing can be deployed across OTN devices.

FlexE is compatible with Optical Transport Network (OTN) and can be used for long-haul slicing across OTN.

❌ D. Only channelized sub-interface-based network slicing can be deployed across MSTP devices.

Incorrect! While MSTP supports channelized interfaces, FlexE is not restricted to MSTP deployment.

Reference from Huawei HCIE-Datacom Documentation:

Huawei FlexE Technology Whitepaper – Network Slicing in Transport Networks

HCIE-Datacom Training Material – Channelized Sub-Interface and FlexE in Network Slicing

VXLAN networks suffer from ARP flooding because ARP requests are broadcasted across all VTEPs in a Layer 2 domain. To reduce ARP flooding, the following mechanisms can be enabled:

✅ A. Local Proxy ARP

Allows the local VTEP to respond to ARP requests without forwarding them across the VXLAN network.

The VTEP caches MAC-IP mappings and replies directly to ARP requests, reducing unnecessary flooding.

✅ B. ARP Broadcast Suppression

Converts ARP broadcast packets into unicast or multicast packets to minimize network-wide flooding.

✅ C. Host Information Collection

Collects and stores MAC-IP bindings of endpoints, which can be used by proxy ARP to reduce flooding.

Incorrect Answer:

❌ D. Port Isolation

Port isolation prevents communication between devices within the same VLAN but does not help reduce ARP flooding between VTEPs.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN Configuration Guide – ARP Optimization Techniques

HCIE-Datacom Training Material – Reducing ARP Broadcasts in VXLAN Networks

For OSPF neighbors to reach Full state, they must exchange LSAs (Link State Advertisements) properly and synchronize their databases.

Possible Causes Preventing OSPF from Entering Full State:

✅ A. A link works abnormally

If the physical or Layer 2 link is unstable, OSPF Hello packets may be lost, preventing the Full state.

✅ B. The OSPF network types on both ends of the link are inconsistent

OSPF network types (Broadcast, P2P, NBMA, etc.) must match on both ends.

Example: If one router is P2P and the other is Broadcast, adjacency issues occur.

✅ C. The router IDs of neighbors are the same

Router ID conflicts prevent OSPF adjacencies from forming.

Each router must have a unique Router ID.

✅ D. The OSPF MTU values of interfaces on both ends of the link are different

If MTU settings do not match, OSPF Database Description (DD) packets may be dropped, preventing Full state.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPF Configuration Guide – Troubleshooting OSPF Neighbor Issues

HCIE-Datacom Study Material – OSPF Adjacency and Route Synchronization

Dynamic VLAN Authorization in Huawei CloudCampus

Dynamic VLAN assignment allows users to be placed into specific VLANs based on authentication methods, ensuring security and network segmentation.

Correct Explanations:

✅ A. Wired users using 802.1X authentication receive VLAN assignments dynamically.

After authentication, the access control system (e.g., iMaster NCE-Campus) assigns VLANs dynamically.

✅ C. Wireless users using 802.1X authentication also receive VLAN assignments.

Similar to wired users, wireless 802.1X authentication allows dynamic VLAN assignment via the RADIUS server.

✅ D. Wired users using MAC authentication can receive VLAN assignments.

If a user does not support 802.1X, MAC authentication can still be used to assign VLANs dynamically.

Incorrect Statement Explanation:

❌ B. When wireless users pass Portal authentication, they join the authorization VLANs delivered to edge nodes.

Wrong! In Portal authentication, VLAN assignment is not dynamically delivered because Portal authentication typically applies access policies, not VLAN changes.

Dynamic VLAN assignment is mainly used with 802.1X or MAC authentication.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Configuration Guide – Dynamic VLAN Assignment and Authentication

HCIE-Datacom Training Material – VLAN Authorization in Virtualized Campus Networks

To determine R3’s role (Level-1, Level-2, or Level-1-2) based on the provided output of the display ipv6 routing-table protocol isis command on R3, we need to analyze the IS-IS routing information and understand IS-IS hierarchy and behavior, particularly in the context of IPv6 routing. Let’s break it down step by step:

Understanding the IS-IS Levels and Hierarchy:

IS-IS (Intermediate System to Intermediate System) is a link-state routing protocol that supports a two-level hierarchy:

Level-1: Routers within the same area, responsible for intra-area routing. Level-1 routers only maintain routing information for their area and rely on Level-1-2 routers to reach other areas.

Level-2: Routers that form the backbone, connecting different areas for inter-area routing. Level-2 routers maintain routing information across areas.

Level-1-2: Routers that operate both at Level-1 (within their area) and Level-2 (to connect to other areas). These routers act as boundary routers between Level-1 areas and the Level-2 backbone.

A router’s role (Level-1, Level-2, or Level-1-2) determines which types of adjacencies it can form and what routing information it advertises or receives.

Analyzing the Output:

The output shows R3’s IPv6 routing table with routes learned via IS-IS, specifically:

Destination: 2082:EDFC:DDCC::B824:0/127, Protocol: ISIS-L1

This route is learned via IS-IS Level-1 (ISIS-L1), indicating that R3 has a Level-1 adjacency and is receiving or advertising routes within its area.

The next hop (FE80::2E0:FCFF:FE45:6A3E) and interface (GigabitEthernet0/0/0) suggest this route is intra-area.

Destination: 2082:EDFC:DDCC::B891:0/127, Protocol: ISIS-L2

This route is learned via IS-IS Level-2 (ISIS-L2), indicating that R3 has a Level-2 adjacency and is receiving or advertising routes for inter-area or backbone routing.

The next hop (FE80::2E0:FCFF:FE50:406F) and interface (GigabitEthernet0/0/1) suggest this route is for a different area or the backbone.

Both Level-1 and Level-2 routes are present in R3’s routing table, which provides critical insight into R3’s role.

Determining R3’s Role:

Level-1 Routers:

Level-1 routers only participate in Level-1 adjacencies and maintain routing information for their area. They do not have Level-2 routes or adjacencies unless connected to a Level-1-2 router. Since R3 has a Level-2 route (ISIS-L2), it cannot be exclusively a Level-1 router.

Level-2 Routers:

Level-2 routers focus on inter-area routing and typically do not maintain Level-1 routes unless they are also configured as Level-1-2. Since R3 has a Level-1 route (ISIS-L1), it cannot be exclusively a Level-2 router.

Level-1-2 Routers:

Level-1-2 routers operate both at Level-1 (for intra-area routing) and Level-2 (for inter-area routing). They can form adjacencies with both Level-1 and Level-2 neighbors and maintain both types of routes. The presence of both ISIS-L1 and ISIS-L2 routes in R3’s routing table indicates that R3 is participating in both Level-1 and Level-2 adjacencies, making it a Level-1-2 router.

Evaluating Each Option:

A. R3 must be a Level-2 device.

This is incorrect because R3 has ISIS-L1 routes, indicating it is also participating in Level-1 adjacencies, which Level-2-only devices do not do. Level-2 devices focus solely on inter-area routing and do not maintain Level-1 routes.

B. The device role of R3 cannot be determined.

This is incorrect because the presence of both ISIS-L1 and ISIS-L2 routes in the routing table clearly indicates R3’s role. The combination of Level-1 and Level-2 routes confirms R3 is a Level-1-2 router.

C. R3 must be a Level-1-2 device.

This is correct. The routing table shows both ISIS-L1 (Level-1) and ISIS-L2 (Level-2) routes, meaning R3 is operating as both a Level-1 and Level-2 router, which defines a Level-1-2 device.

D. R3 must be a Level-1 device.

This is incorrect because R3 has ISIS-L2 routes, indicating it is also participating in Level-2 adjacencies, which Level-1-only devices do not do. Level-1 devices only maintain intra-area routes and rely on Level-1-2 routers for inter-area reachability.

Additional Considerations:

The Flags: D in the output typically indicates a directly connected route or a route downloaded to the forwarding table, but it does not affect the determination of R3’s IS-IS level.

The preference (15) and cost (20) are standard for IS-IS routes and do not impact the level determination.

In Huawei’s IS-IS implementation, routers can be configured explicitly as Level-1, Level-2, or Level-1-2 using commands like isis level-1-2 under the IS-IS process. The presence of both Level-1 and Level-2 routes confirms R3’s configuration as Level-1-2.

Huawei HCIE-Datacom Context:

According to Huawei HCIE-Datacom documentation, IS-IS routers can operate at different levels, and the routing table’s protocol type (ISIS-L1 or ISIS-L2) indicates the level of adjacency. A router with both Level-1 and Level-2 routes is necessarily a Level-1-2 device, as it participates in both intra-area and inter-area routing.

The display ipv6 routing-table protocol isis command on Huawei devices shows routes learned via IS-IS, and the protocol type (L1 or L2) directly reflects the router’s role in the IS-IS hierarchy.

Conclusion:

Based on the presence of both ISIS-L1 and ISIS-L2 routes in R3’s IPv6 routing table, R3 must be a Level-1-2 device, as it is participating in both Level-1 (intra-area) and Level-2 (inter-area) adjacencies. Therefore, the correct answer is C.

References to Huawei HCIE-Datacom Documents:

Huawei HCIE-Datacom V1.0 Training Material, Chapter on IS-IS Configuration and Hierarchy.

Huawei NE Series Router Configuration Guide, IS-IS Section (Level-1, Level-2, and Level-1-2 Operations).

Huawei Technical Whitepaper on IS-IS Protocol, discussing IPv6 Routing and Level Determination.

Congestion Management (like WFQ, CBWFQ) controls traffic without discarding packets unless absolutely necessary.

Congestion Avoidance (e.g., WRED) is responsible for selectively discarding packets to prevent buffer overflow.

Key Distinction:

Congestion Management = Traffic queuing and prioritization (no packet loss).

Congestion Avoidance = Selectively dropping packets (e.g., WRED).

✅ Reference: Huawei HCIE-Datacom Guide - Congestion Management vs. Avoidance

In firewall hot standby (HRP - Hot Standby Routing Protocol) mode, certain data can be synchronized between the active and standby firewalls to ensure uninterrupted service.

The following data is backed up:

✅ Server mapping table: Contains information about NAT mappings and other session mappings.

✅ AAA user table (excluding the default user admin): Ensures that authenticated users do not need to re-authenticate in case of failover.

✅ Session table: Ensures that existing connections remain active when switching to the standby firewall.

❌ Dynamic MAC address table is NOT backed up because it is dynamically learned and not relevant to firewall session synchronization.

✅ Reference: Huawei HCIE-Datacom Guide - Firewall HRP Synchronization

Huawei Open Programmability System (OPS) and HTTP Request Headers

Huawei OPS allows network automation and programmability through HTTP-based APIs. When using Python scripts to send HTTP requests to network devices, the request headers must specify the content format for data exchange.

✅ B. Content-Type: text/json, Accept: text/json (Correct Answer)

Content-Type: text/json → Specifies that the request body contains JSON-formatted data.

Accept: text/json → Specifies that the response should be in JSON format.

Understanding MPLS Forwarding Mechanism

MPLS (Multiprotocol Label Switching) is a high-performance forwarding mechanism that operates on two planes:

1️⃣ Control Plane:

Establishes Label Switched Paths (LSPs) using protocols like LDP (Label Distribution Protocol), RSVP-TE (Resource Reservation Protocol - Traffic Engineering), or BGP-LU (BGP Label Unicast).

Assigns labels to packets based on routing policies.

2️⃣ Data Plane (Forwarding Plane):

Uses a Label Forwarding Information Base (LFIB) instead of traditional IP routing.

Packets are forwarded based on labels, not IP addresses.

Analysis of the Answer Choices

✅ C. The system automatically assigns an ID to the upper-layer application that uses a tunnel. This ID is also called the tunnel ID.

Correct: MPLS assigns a Tunnel ID to applications that utilize tunnels (e.g., VPNs, MPLS-TE, or L2/L3 services).

This ID helps differentiate between various tunnel applications, ensuring traffic follows the correct LSP.

❌ A. After an IP packet enters an MPLS domain, the MPLS device forwards the packet based on FIB table queries.

Incorrect: MPLS routers do NOT use the FIB (Forwarding Information Base) for forwarding once labels are assigned.

Instead, they use LFIB (Label Forwarding Information Base) to switch packets based on labels.

❌ B. If the tunnel ID is 0x0, the MPLS forwarding process starts.

Incorrect: If the Tunnel ID is 0x0, MPLS does NOT start; it means no label is assigned, and traditional IP forwarding occurs.

❌ D. If the tunnel ID is not 0x0, the normal IP forwarding process starts.

Incorrect: If the Tunnel ID is not 0x0, MPLS forwards traffic using label switching, not IP forwarding.

IS-IS (Intermediate System to Intermediate System) protocol has a limit on the size of Link-State PDUs (LSPs).

Why Fragmentation?

LSPs contain routing and topology information.

If the LSP exceeds the maximum size, fragmentation allows the device to store and forward more routes by breaking them into smaller LSPs.

Key Point: IS-IS fragmentation is essential in large-scale networks where routing tables grow beyond the default LSP size limit.

✅ Reference: Huawei HCIE-Datacom Guide - IS-IS Protocol and Route Scaling

Forwarding Equivalence Class (FEC) is a key concept in MPLS (Multiprotocol Label Switching), where packets with the same forwarding characteristics are grouped into an FEC and assigned a label.

Correct Answers (Cannot be Used for FEC Allocation):

A. Fragment Offset – Incorrect as an FEC allocation standard

Fragment offset is used for reassembling fragmented IP packets at the receiver side.

It is not relevant for MPLS label assignment.

B. Application Protocol – Incorrect as an FEC allocation standard

MPLS does not classify packets based on application-layer protocols (e.g., HTTP, FTP).

It works mainly at Layer 2 and Layer 3.

Incorrect Answers (Valid FEC Allocation Standards):

C. Destination Address – Valid FEC allocation criterion

One of the most common MPLS FEC classifications.

Packets with the same destination are grouped into the same FEC.

D. Class of Service (CoS) – Valid FEC allocation criterion

MPLS uses CoS-based traffic classification (e.g., Exp bits in MPLS headers).

Different CoS levels can be mapped to different labels.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS Technology Guide – FEC and Label Assignment

HCIE-Datacom MPLS VPN Configuration Guide

IGP Metric Design in Enterprise WANs

In an enterprise bearer WAN, routing metrics determine path selection. The aggregation layer connects multiple access-layer devices to the core network, so it should have a lower metric to:

✅ Ensure traffic is forwarded through higher-capacity aggregation links instead of lower-bandwidth access links.✅ Optimize traffic flow, reduce congestion, and improve network efficiency.✅ Enhance reliability by preferring more stable aggregation links.

IGP Routing Protocols Considerations:

OSPF: Lower cost values indicate preferred paths.

IS-IS: Lower link metrics result in preferred forwarding paths.

Reference from Huawei HCIE-Datacom Documentation:

Huawei IGP Design Guide – Enterprise WAN Routing Optimization

HCIE-Datacom Training Material – Metric Calculation and Path Selection in OSPF/IS-IS

Why is Free Mobility Not Based on VLANs or IP Addresses?

Free mobility in Huawei CloudCampus implements policy-based user access control based on user identity (rather than VLANs or IP addresses).

Users can move across different network locations while maintaining their assigned security and access policies.

✅ How Free Mobility Works:

Policies are applied based on User Groups instead of VLAN or IP.

Uses Group-Based Policy Control (GBP) and Software-Defined Access (SDA) principles.

❌ Incorrect Statement Explanation:

Traditional networks rely on VLANs and IP addresses for segmentation, but Free Mobility applies policies at the user level, allowing seamless access anywhere on the network.

Reference from Huawei HCIE-Datacom Documentation:

Huawei CloudCampus Solution Guide – Free Mobility and Policy Control

HCIE-Datacom Training Material – Identity-Based Networking

Understanding OSPF Neighbor States

OSPF (Open Shortest Path First) establishes neighbor relationships through several states:

1️⃣ Down: No Hello packets received.2️⃣ Init: Router receives Hello packets but its own Router ID is missing in the received packets.3️⃣ 2-Way: Routers see each other in Hello packets. (Stable state for non-DR/non-BDR routers).4️⃣ ExStart: Routers start exchanging LSAs but may face MTU mismatches.5️⃣ Exchange: Routers send Database Description (DBD) packets to synchronize link-state databases.6️⃣ Loading: Routers exchange Link-State Requests (LSRs) & Updates (LSUs) to fully sync.7️⃣ Full: Routers are fully synchronized.

Analysis of the Answer Choices

✅ A. For non-DR and non-BDR routers on an Ethernet link, the 2-Way state is acceptable.

Correct: Non-DR/Non-BDR routers remain in 2-Way state since they don’t need to form full adjacency.

✅ B. The Init state indicates that the router has received Hello packets from its neighbors, but the received Hello packets do not contain the OSPF RID of the receiving router.

Correct: If an OSPF router receives a Hello but does not see its own Router ID, it stays in the Init state.

✅ C. The ExStart state indicates that two neighbor routers have inconsistent MTUs or the same OSPF Router ID (RID).

Correct: If MTUs mismatch or RIDs conflict, the DBD exchange fails, causing routers to remain in ExStart state.

❌ D. The Attempt state indicates that the router does not send unicast Hello packets to configured neighbors.

Incorrect:

In Attempt state, routers send unicast Hello packets to manually configured neighbors (common in NBMA networks).

If no Hello responses are received, they remain in Attempt state, but they DO send Hellos.

Real-World Application

OSPF Troubleshooting: Identifying routers stuck in Init or ExStart states can point to MTU mismatches or neighbor misconfigurations.

NBMA Networks (Frame Relay, DMVPN): Manually configured neighbors may stay in Attempt state if Hello packets are lost.

✅ Reference: Huawei HCIE-Datacom Study Guide – OSPF Neighbor States & Troubleshooting

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

6PE (IPv6 Provider Edge over MPLS) vs. 6VPE (IPv6 VPN Provider Edge over MPLS VPNs)

6PE (IPv6 over MPLS without VPNs):

Uses global IPv6 routing over MPLS.

No VPN instances (VRFs) are created on PEs.

IPv6 addresses cannot be reused across different CEs because all traffic is routed using a single global table.

6VPE (IPv6 over MPLS with VPNs):

Uses MPLS VPN (VRF instances) to provide IPv6 VPN services.

VPN instances (VRFs) are created on PEs to separate customer networks.

IPv6 addresses of CEs can be reused in different VPN instances because each VRF maintains separate routing tables.

Correct Answer Explanation:

✅ C. In 6VPE networking, IPv6 addresses of a CE can be reused.

Since each VPN instance (VRF) maintains its own IPv6 routing table, IPv6 addresses of CEs can be reused across different VPNs.

Incorrect Answer Explanations:

❌ A. In 6PE networking, VPN instances need to be created on PEs.

Wrong! 6PE does not use VPN instances (VRFs); it relies on a global IPv6 routing table.

❌ B. In 6PE networking, IPv6 addresses of a CE can be reused.

Wrong! Since 6PE uses a single IPv6 global routing table, IPv6 addresses cannot be reused.

❌ D. In 6VPE networking, no VPN instance needs to be created on PEs.

Wrong! 6VPE requires VPN instances (VRFs) on PEs to separate customer traffic.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – 6PE and 6VPE Deployment

HCIE-Datacom Training Material – IPv6 MPLS Solutions

OSPFv3 (for IPv6) introduces significant changes compared to OSPFv2 (for IPv4).While both versions share similar routing mechanisms, there are key LSA format and functional differences beyond just address changes.

Major Differences Between OSPFv2 and OSPFv3:

Address Independence (LSA Format Changes)

OSPFv3 LSAs do not contain IP addresses directly; they rely on Link-LSA and Intra-Area Prefix LSA to advertise addresses.

In OSPFv2, IP addresses were included in LSA headers.

New LSA Types in OSPFv3

LSA Type 8 (Link-LSA): Advertises a router’s IPv6 address to neighbors.

LSA Type 9 (Intra-Area Prefix LSA): Replaces the address information in Router-LSAs and Network-LSAs.

Support for Multiple Address Families (AF)

OSPFv3 can support both IPv4 and IPv6 in newer implementations (RFC 5838).

Authentication Mechanism Removed

OSPFv3 relies on IPsec for authentication, whereas OSPFv2 had built-in authentication mechanisms.

Incorrect Statement Explanation:

❌ The statement "LSA formats and functions remain unchanged" is false because:

LSA structures were modified in OSPFv3.

New LSA types were introduced to handle IPv6 addresses separately.

Reference from Huawei HCIE-Datacom Documentation:

Huawei OSPFv3 Configuration Guide – LSA Differences from OSPFv2

HCIE-Datacom Study Material – OSPFv3 Evolution & IPv6 Implementation