Huawei H12-891_V1.0 - HCIE-Datacom V1.0

Comprehensive and Detailed In-Depth Explanation:1. Understanding SRv6 (Segment Routing over IPv6):SRv6 uses theIPv6 headeralong with an additionalSRH (Segment Routing Header)to implement segment routing within an IPv6 network. The SRH contains:Segment List (SL):A list of IPv6 addresses (segments) to traverse.SL (Segments Left):An integer that indicates thenumber of segmentsyet to be visited.Active Segment:Thenext IPv6 addressin the segment list, stored in theDestination Addressfield of the IPv6 header.2. Analyzing the Given Scenario:Thesegment list (SL)in the SRH header shows:FC04::400FC04::4FC03::3The segment list is processed inreverse order(from bottom to top).SL (Segments Left)indicates theindex of the active segmentin the list.TheDestination Addressin the IPv6 header is currentlyFC04::4, indicating that theactive segmentis thesecond elementin the list.3. Determining the Value of SL:Theindexingin the segment list starts from0.SinceFC04::4is thesecond segment (from the bottom), the value ofSLwill be1.This means that1 segment is leftto be processed after the current one (FC04::4).Once the packet reachesFC04::4, theSL value will decrement to 0, and the next segment (FC03::3) will be processed.4. Why the Answer is 1:TheSL value decreases as segments are processed.As the currentactive segmentis thesecond in the list (from the bottom), theSL value is 1.

Comprehensive and Detailed In-Depth Explanation:

The statementAis incorrect because enablingDHCP snooping in the VLAN viewonly takes effect on interfaces within that specific VLAN that have DHCP snooping configured. It doesnot automatically apply to all interfaces of the device. Each interface within the VLAN must individually be configured or marked as trusted/untrusted.

B:Correct, as DHCP snooping, when enabled globally without any additional specifications, defaults to processingDHCPv4messages.

C:Correct, as DHCP snooping can protect against DHCP spoofing attacks by marking interfaces astrustedoruntrusted.

D:Correct, enabling DHCP snooping on an interface means it will monitor all DHCP messages on that specific interface.

Understanding the Telemetry Output:

Dest-addr: 192.168.56.1→The destination IP address is 192.168.56.1.✅

Dest-name: Dest1→The destination group name is Dest1.✅

Protocol: gRPC→Data push uses the gRPC protocol.✅

Vpn-name: - (empty)→No VPN encapsulation is used.❌

Incorrect Answer Explanation:

❌C. "VPN encapsulation is used for data push"→Incorrect!

The Vpn-name field isempty, indicating thatVPN encapsulation is NOT enabled for telemetry data transport.

Reference from Huawei HCIE-Datacom Documentation:

Huawei Telemetry Configuration Guide – Destination and Data Push Methods

HCIE-Datacom Study Material – gRPC and Telemetry Data Streaming

VXLAN tunnel configuration, you donot use a control planelike BGP EVPN. Instead, youmanually configureall necessary forwarding parameters, including:VNI (VXLAN Network Identifier): Identifies the VXLAN segment.VTEP IP Address: The remote tunnel endpoint.Ingress Replication List: Required for multicast emulation (flooding/BUM traffic) in the absence of a multicast control plane.Whenconfiguring statically, theVNIis essential to map Layer 2/3 services to the correct VXLAN segment.Thus, the correct word to complete the sentence is:VNICorrect answer: VNI

Comprehensive and Detailed In-Depth Explanation:

The diagram shows aWAN networkwhereSegment Routing (SR)is used in conjunction with theiMaster NCEcontroller. The network consists ofData Centers (DCs),Branches,Provider Edge (PE)routers, andRoute Reflectors (RR)withinAS 65600. Let's analyze each network technology and its placement in the scenario.

1. BGP-LS (Border Gateway Protocol - Link State):

Application Location:1 (PE to RR)

BGP-LS is used tocollect and distribute network topology informationfrom theIGP (Interior Gateway Protocol)domain.

It enables theiMaster NCE(controller) to learn about the network topology and SR information from PE routers.

The PE routers send theirlink-state informationto theRRusingBGP-LS.

Why Location 1:

The RR collects topology data from PEs and forwards it to the controller for path computation.

2. BGP (Border Gateway Protocol):

Application Location:2 (RR to iMaster NCE)

Standard BGP is used forroute distributionandnetwork connectivity.

The RR usesBGPto exchange route information with thecontroller(iMaster NCE).

Why Location 2:

TheRRaggregates routes and exchanges them with the iMaster NCE for centralized management.

3. MP-IBGP (Multiprotocol Internal BGP):

Application Location:3 (PE to PE)

MP-IBGP is used toexchange VPNv4 and VPNv6 routesbetween PE routers within thesame AS.

It allows PEs toadvertise VPN routesacross thebackbone network.

Why Location 3:

PEs need to communicate VPN-related information within the AS, ensuring end-to-end connectivity between DCs and branches.

4. BGP SR-Policy/PCEP (Path Computation Element Protocol):

Application Location:4 (iMaster NCE to PE)

BGP SR-Policy andPCEPare used by thecontrollertodistribute SR policiesto the PE routers.

TheiMaster NCEcalculates optimal paths and sends the SR policies to PEs viaBGP SR-PolicyorPCEP.

Why Location 4:

The controller programs theSegment Routing pathsdirectly to the PEs for optimal traffic engineering.

Why This Mapping Is Correct:

The mapping is based on theroles and functions of each protocolwithin theSR-based WAN architecture. The controller uses BGP-LS to learn topology, BGP for route reflection, MP-IBGP for VPN route exchange, and BGP SR-Policy/PCEP for path computation and distribution.

✅A. encoding: indicates the character set encoding format. Currently, only UTF-8 encoding is supported.

UTF-8 is the default and only supported character encoding in NETCONF XML.

✅B. /: indicates the end of the current tag.

In XML, closes an element, defining the end of a structure.

✅C.

The

✅D. ?>: indicates the end of an instruction.

Closes theXML declaration.

Reference from Huawei HCIE-Datacom Documentation:

Huawei NETCONF Development Guide – XML Formatting Rules

HCIE-Datacom Training Material – Understanding XML in Network Automation

Understanding Network Security for Authorized User Access

🔹Problem Scenario:

Only authorized users should be allowed network access.

Users can obtain IP addresses either via DHCP or a predefined static IP list.

Unauthorized users (e.g., attackers using rogue DHCP servers or spoofed IPs) must be blocked.

🔹Required Technologies for Securing Access:

1️⃣DHCP Snooping– Protects againstrogue DHCP serversand builds abinding table of legitimate DHCP clients.

2️⃣IP Source Guard (IPSG)– Ensures that onlyauthorized IP-MAC bindingscan send traffic.

Analysis of the Answer Choices:

❌A. DAI + Port Security (Incorrect)

DAI (Dynamic ARP Inspection)prevents ARP spoofingbut doesnot validate IP-MAC-DHCP bindings.

Port Securityonlylimits MAC addresses per portbut doesnot verify IP addresses.

Does NOT protect against unauthorized static IP users.

✅B. DHCP Snooping + IPSG (Correct)

DHCP Snooping:

Preventsrogue DHCP servers from assigning unauthorized IPs.

Builds aDHCP binding table(IP-MAC-Port).

IP Source Guard (IPSG):

Blocks trafficfrom IPs not listed in the DHCP snooping binding table.

Can be configured to allow manually specified static IP addresses.

Best choice to allow only authorized users (both DHCP and static IP users).

❌C. DHCP Snooping + DAI (Incorrect)

DAI (Dynamic ARP Inspection) prevents ARP spoofingbutdoes not block unauthorized static IP users.

Lacks IP-level access controlneeded to enforce static IP policies.

❌D. DAI + IPSG (Incorrect)

IPSG (IP Source Guard) needs DHCP Snooping to build the binding table.

Without DHCP Snooping, IPSG cannot function properly.

DAI does not provide complete protection against unauthorized users.

Why is the Answer B (DHCP Snooping + IPSG)?

✅Ensures only users assigned a DHCP IP (or authorized static IPs) can send traffic.

✅Blocks rogue DHCP servers and unauthorized static IP users.

Real-World Application:

Enterprise Networks:Prevents unauthorizedstatic IP users or attackers from accessing VLANs.

Public Wi-Fi Security:Ensures onlyauthorized users receive IPs and can send traffic.

✅Reference:Huawei HCIE-Datacom Guide – DHCP Snooping and IPSG Security Mechanisms

Huawei SD-WAN supports various intelligent traffic steering mechanismsto optimize link utilization andbalance network trafficacross multiple links.

✅D. Traffic bandwidth-based traffic steering

This method ensures that traffic isdistributed across multiple links based on available bandwidth.

SD-WAN dynamically selects linksbased on their real-time bandwidth utilization,ensuring optimal performance and 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:

OSPFv3does not use ASBR-Summary-LSA. Instead, it introduces newInter-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).

SinceASBR-Summary-LSA (Type 4) does not exist in OSPFv3, the correct answer isA.

📖Reference:Huawei HCIE Datacom – OSPFv3 LSA Types

Comprehensive and Detailed In-Depth Explanation:

In large- and medium-sized campus networks,Multi-mode authenticationis commonly used for PCs connected to IP phones. This is because multi-mode authentication allows:

Multiple authentication methods on the same interface,such as MAC address authentication for the IP phone and802.1X authentication for the PC.

This setup is ideal for scenarios where both devices share a single network port but require different authentication mechanisms.

MAC address authentication (A)and802.1X authentication (B)individually cannot accommodate both devices efficiently.

Portal authentication (D)is mainly used for guest access and is not practical for IP phone and PC connections.