BGP EVPN Route Types in VXLAN:

BGP EVPN Type 2 Route (MAC/IP Advertisement Route)

Used forhost reachability advertisement.

Carries MAC and IP address information of endpoints.

Does not carry an IP Prefix field(Type 5 routes handle prefixes).

Correct Explanation of Answer Choices:✅IP Address (B) is included– Used for host mobility and reachability.✅L3VNI (C) is included– Used forLayer 3 VXLAN routing.✅L2VNI (D) is included– Used forLayer 2 VXLAN bridging.❌IP Prefix (A) is not included in Type 2 routes– It is part ofEVPN Type 5 routesforprefix advertisement.

Reference from Huawei HCIE-Datacom Documentation:

Huawei VXLAN BGP EVPN Configuration Guide – Type 2 vs. Type 5 Routes

HCIE-Datacom Training Material – VXLAN Overlay Networks and BGP EVPN

To automatically enable MPLS on an interface inSR-MPLS:

Segment routing must be enabled globallyin thesystem view→✅

Segment routing must also be enabled under the IGP process, andIGP (OSPF or IS-IS) must be enabled on the interface→✅

Clarifications:

SRGB (Segment Routing Global Block)configuration defines SID ranges butdoes not trigger MPLS enablement→❌

Static adjacency labelsare advanced options and do not auto-enable MPLS →❌

Correct answers: B, D

The basic constructs in YANG data modeling include:

Leaf node – A single data element with a specific type (e.g., integer, string).

List node – A repeating set of elements, each structured the same.

Incorrect options:

A. Set node – ❌ Not a valid YANG construct.

D. Tree node – ❌ Not an individual data model element. The entire model forms a tree structure, but there is no “tree node” in YANG syntax.

Exact Extract – Huawei YANG Modeling Fundamentals:

“YANG defines elements such as leaf, list, container, choice, and leaf-list. 'Set' and 'tree' are not YANG node types.”

InMPLS VPN, packets are forwarded usingtwo labels:

Outer label (Transport Label)– Used by the MPLS backbone for forwarding.

Inner label (VPN Label)– Used by theegress PEto identify the correct VPN instance.

Explanation of Correct Options:

✅A. The egress PE sends the data packet to the correct VPN based on the inner label.

Theinner label is assigned by the egress PEand determines the final destination VPN instance.

✅B. The penultimate hop removes the outer label before forwarding the data packet to a peer egress PE.

Penultimate Hop Popping (PHP)occurs when thesecond-to-last router(P router) removes the outer MPLS label before forwarding to theegress PE.

This reduces theprocessing overheadon the egress PE.

✅D. The penultimate-hop device receives a packet with an outer label.

Theouter label is used to forward the packet across the MPLS backbone.

Before reaching the egress PE, thepenultimate router still has the outer labeland processes it.

Incorrect Option:

❌C. The IP data packet received by the egress LSR is without labels.

This isincorrectbecause theinner label (VPN label) is still presentwhen the packet reaches the egress PE.

Only theouter labelis removed by PHP, not the inner VPN label.

Reference from Huawei HCIE-Datacom Documentation:

Huawei MPLS VPN Configuration Guide – Label Processing

HCIE-Datacom MPLS Traffic Engineering and PHP Mechanism

Huawei iMaster NCE-Campus MPLS VPN Implementation Guide

ForOSPF neighbors to reach Full state, they must exchangeLSAs (Link State Advertisements) properlyand synchronize their databases.

Possible Causes Preventing OSPF from Entering Full State:

✅A. A link works abnormally

If thephysical or Layer 2 linkis unstable,OSPF Hello packetsmay 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 matchon both ends.

Example: If one router isP2Pand the other isBroadcast, adjacency issues occur.

✅C. The router IDs of neighbors are the same

Router ID conflicts prevent OSPF adjacencies from forming.

Each router must have aunique 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

Understanding HTTP/1.1 Response Structure

????What is an HTTP Response?

The response issent from the server to the client after processing an HTTP request.

The structure follows astandardized format:

Elements of an HTTP/1.1 Response:

✅A. Status Line→ Containsprotocol version, status code, and reason phrase.

✅B. Response Body→ ContainsHTML, JSON, XML, or other content.

✅C. Response Header→ Providesmetadata about the response(e.g., Content-Type, Server).

✅D. Empty Line→ Ablank line separates headers from the response body.

Example of an HTTP/1.1 Response:

HTTP/1.1 200 OK

Date: Sat, 08 Mar 2025 14:00:00 GMT

Server: Apache/2.4.41 (Ubuntu)

Content-Type: text/html; charset=UTF-8

Welcome to Huawei Datacom

Why is the Answer A, B, C, D?

✅An HTTP response includes a status line, headers, an empty line, and a response body.

Real-World Application:

Web Application Debugging:Helps developersanalyze server responses.

API Security:Validatesresponse headers to prevent injection attacks.

✅Reference:Huawei HCIE-Datacom Guide – HTTP Protocol and Response Headers

InHTTP status codes:

401 Unauthorized: The server has received the request butrequires authentication. This typically means:

No token or credentials were provided.

Credentials/token were incorrect or expired.

Other options:

403 (Access Denied)would mean correct credentials butinsufficient permissions.

404: Resource does not exist.

503: Service unavailable.

Correct answer: A. Unauthorized

Traffic Diversion in SR-MPLS Policy

SR-MPLS Policiesuse traffic steering mechanismsto direct specific flows toSegment Routing paths (SR Policies). When multiple services share thesame destination address,color-based traffic diversionensuresdifferentiated service treatment.

✅B. Color-based traffic diversion (Correct Answer)

Traffic is classified based on "color" (a BGP-SR policy attribute) and mapped to different SR-MPLS tunnels.

Different colors represent different paths(e.g., high-priority services can use an optimized low-latency path).

This method ensures service qualityby directing traffic according topolicy-based routing decisions.

Comprehensive and Detailed Explanation:

✔Inter-VN communicationallows users indifferent VNs (R&D and Marketing)to communicate.

✔Correct Steps:

✅(B) Deploy a Policy Control Matrix→ Definesrules for inter-VN communicationbetween security groups.

✅(C) Configure Inter-VN Communication→ Enablesrouting between VNsthrough theborder gateway or firewall.

✔Why Not Other Options?

❌(A) Deploy Network Service Resources→ This is forinternal VN service deployment, not inter-VN communication.

❌(D) Deploy an External Network→ This is forInternet or WAN access, not internal VN-to-VN communication.

????Reference:Huawei HCIE Datacom – Virtual Network Intercommunication

Understanding EVPN (Ethernet VPN) Label Allocation and ARP Handling

????What Happens in This Scenario?

1️⃣CE1 (192.168.1.1) sends an ARP request to discover the MAC address of CE2 (192.168.1.2).

2️⃣PE1 receives the ARP request and needs to forward it over the EVPN fabric.

3️⃣To send the broadcast ARP request across the EVPN network, PE1 forwards the packet to PE4 using BUM (Broadcast, Unknown unicast, and Multicast) forwarding.

4️⃣PE4, as the Designated Forwarder (DF), forwards the ARP request to CE2.

Role of Labels in EVPN VXLAN/MPLS Networks

????EVPN uses BGP to distribute MAC/IP reachability information using different route types.

✅EVPN Type 2 Route (MAC/IP Advertisement Route):

Used forMAC-to-IP address mappingannouncements.

Ensuresremote VTEPs (PE routers) learn MAC-to-IP bindingsdynamically.

✅EVPN Type 3 Route (Inclusive Multicast Route):

Used forBUM traffic (Broadcast, Unknown Unicast, Multicast).

Assigns a multicast label (e.g., 201) to be used for forwarding broadcast packets like ARP requests.

????In this case:

Thelabel 201is used forBUM traffic forwarding.

BUM traffic is handled using an EVPN Type 3 route.

Why is the Answer 3?

✅EVPN Type 3 routes carry labels for BUM traffic, which includes ARP requests.

✅Label 201 is used for multicast distribution, which is managed by Type 3 routes.

Real-World Application:

VXLAN Data Centers:UsesEVPN Type 3 routes to control BUM traffic efficiently.

Campus Networks:Preventsunnecessary flooding of ARP requests across VXLAN domains.

✅Reference:Huawei HCIE-Datacom Guide – EVPN BGP Route Types and Multicast Labeling