H12-821_V1.0 HCIP-Datacom-Core Technology V1.0 Questions and Answers

When the level of an IS-IS interface is changed, the adjacency must be re-established because IS-IS adjacencies are formed based on matching levels (Level-1, Level-2, or both). Other changes, such as cost or hello intervals, do not disrupt the existing adjacency but might impact routing metrics or timing ​.

 Silent Interface Explanation

Thesilent-interfacecommand is used to prevent OSPF from sending or receiving OSPF packets on the specified interface (GE 0/0/1). This disables OSPF adjacency establishment and stops route advertisement for that interface.

 Network Observations

Statement A: R2 can access the server.This is correct, as the silent interface does not impact data traffic, only OSPF-related communication.

Statement B: GE 0/0/1 of R1 cannot send OSPF packets.Correct due to thesilent-interfaceconfiguration.

Statement C: The network segment to which GE 0/0/1 of R1 belongs cannot be advertised.This is correct, as the silent interface prevents route advertisement.

Statement D: GE 0/0/1 of R1 cannot accept OSPF packets.Correct, as the silent interface configuration blocks packet reception.

 HCIP-Datacom-Core Reference

OSPF interface command behavior is outlined in the configuration and lab examples sections​​.

The monitoring plane's primary role is environmental monitoring, ensuring the stability of the system. Functions like voltage monitoring, temperature tracking, fan speed control, and power management are standard. These are independent of the forwarding or control planes and critical for maintaining device health in network operations ​.

1 – Idle

2 – Connect

3 – OpenSent

4 – OpenConfirm

5 – Established

6 – Active

TheBGP finite state machinedefines how a BGP speaker transitions through various states when establishing and maintaining a BGP session. Below is the role of each state:

Idle (1)– BGP is waiting to start a connection. Initial state of the BGP process.

Connect (2)– BGP initiates a TCP connection to the peer.

OpenSent (3)– TCP connection is established; BGP sends an OPEN message and waits for one from the peer.

OpenConfirm (4)– BGP has received a valid OPEN message and is now expecting a KEEPALIVE.

Established (5)– BGP session is fully established; UPDATE messages can now be exchanged.

Active (6)– If the TCP connection fails in Connect state, BGP transitions to Active and will retry connection.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“BGP goes through the following states in order: Idle → Connect → Active → OpenSent → OpenConfirm → Established. The transition depends on the success or failure of TCP connection setup and BGP message exchanges.”

(Chapter: BGP Principles – Section: BGP State Machine)

The preference of routing protocols determines the selection order of routes when a router receives multiple routes to the same destination from different routing protocols. For instance, OSPF has a higher preference over RIP, so OSPF routes will be selected first. Huawei routing preferences confirm this behavior ​.

One multicast MAC address maps to 32 multicast IP addresses due to the limited number of bits used in the mapping process. Specifically, the lower 23 bits of the MAC address map to the lower 23 bits of the multicast IP address, while the high 24 bits of the MAC address are fixed as 0x01005E. Thus, Option B is false ​.

The information provided indicates that the configured query interval is 60 seconds, which applies to general queries. Group-specific queries are sent at a shorter interval, usually derived from the maximum response time. Therefore, the statement about a 60-second interval for group-specific queries is false. Other statements regarding maximum response time (10s), IP address, and IGMP version (V2) are correct ​.

OSPF (Open Shortest Path First) mandates that the backbone area (Area 0) serves as the central area for routing information exchange. To avoid inter-area routing loops, routing information is only exchanged between the backbone area and non-backbone areas, not directly between two non-backbone areas. Consequently, each Area Border Router (ABR) must connect to the backbone area to facilitate this routing exchange ​.

TheDHCPNAKmessage is sent by the DHCP server to the client to indicate that the requested configuration is not valid. Messages likeDHCPDiscover,DHCPRequest, andDHCPReleaseare initiated by the client in the DHCP process ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. What is NETCONF?

NETCONF (Network Configuration Protocol) is an XML-based protocol used for network device configuration and management.

It enables reading, modifying, deleting, and restoring configurations programmatically.

2. Supported Operations:

Option A: Modifying configurations

Correct.

NETCONF allows you to modify existing configurations on network devices.

Option B: Deleting configurations

Correct.

Configurations can be deleted using NETCONF operations.

Option C: Restoring configurations

Correct.

NETCONF can restore configurations by applying previously saved configuration data.

Option D: Backing up configurations

Correct.

NETCONF can retrieve and save the current configuration as a backup.

3. Summary:

NETCONF supports all listed operations: modifying, deleting, restoring, and backing up configurations.

 IP Prefix List Matching Conditions

An IP prefix list matches based on:

Mask: Specifies the subnet mask length.

Action: Specifies whether to permit or deny.

Index: Orders the rules within the prefix list.

Port numbers are not applicable as matching conditions in an IP prefix list.

 HCIP-Datacom-Core Reference

IP prefix list configurations are detailed in the routing policy and route filtering chapters​​.

The virtual MAC address for a VRRP virtual router is determined by the formula00-00-5E-00-01-[VRID in hexadecimal]. For VRID 3, the hexadecimal equivalent is03. Thus, the virtual MAC address is00-00-5E-00-01-03​.

In BGP, theAS-Pathattribute is mandatory and must be included in allUPDATEmessages. It records the autonomous systems a route has traversed. Attributes likeLocal-Preference,MED, andPrefvalare optional and may not always be included. TheAS-Pathis crucial for loop prevention and route selection ​.

An OSPF AS-external LSA is used to describe routes to networks that are external to the OSPF Autonomous System (AS). This external route information is typically imported into OSPF by anAutonomous System Boundary Router (ASBR).

If theForwarding Addressfield in the AS-external LSA is set to 0.0.0.0, this indicates that traffic destined for the external network should be forwarded directly to the ASBR that advertised the external route.

The specific context mentioned here relates to theNot-So-Stubby Area (NSSA), a type of OSPF area designed to handle AS-external routes in a more controlled way. In NSSAs:

Type 7 LSAs are used to describe AS-external routes.

The ASBR within the NSSA converts the Type 7 LSA to a Type 5 LSA before advertising it to the backbone area.

Hence, the correct acronym for the described functionality isNSSA.

InVRRP HSB (Hot Standby Backup)mode for WLAN deployments (typically between ACs or access controllers),backup of critical dataensures fast failover and minimal service disruption.

A. Real-time backup– Supported. Configuration and session information are synchronized in real-time between the active and standby ACs.

B. Scheduled synchronization–Not supported. HSB requires instant synchronization, not based on a scheduled time.

C. Batch backup– Supported. Some types of less time-sensitive data (e.g., logs or counters) may be backed up in batches.

D. Cloud backup–Not part of HSB functionality. Cloud backup is a separate mechanism, typically used for archival purposes, not real-time failover.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“VRRP HSB mode supports real-time and batch backup between ACs to protect WLAN services. Scheduled and cloud backups are not part of HSB functionality.”

(Chapter: WLAN Reliability – Section: AC Redundancy and HSB Mechanism)

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding Hybrid Interfaces on a Layer 2 Switch:

Layer 2 switches support different interface types, such asaccess,trunk, andhybridinterfaces.

Atrunk interfaceallows traffic from multiple VLANs to pass through, but frames belonging to the native VLAN are sent untagged, while all other VLAN frames are tagged.

Ahybrid interfaceis more flexible:

It allows traffic from multiple VLANs to pass through, just like a trunk interface.

However, you can configure whether frames for specific VLANs are tagged or untagged as they leave the interface. This feature is useful in certain networking scenarios, such as connecting devices that do not support VLAN tagging.

2. Key Differences Between Trunk and Hybrid Interfaces:

A screenshot of a computer Description automatically generated

3. Why the Statement is TRUE:

The statement accurately describes the functionality of a hybrid interface:

It supports traffic from multiple VLANs.

It allows administrators to configure whether outgoing frames are tagged or untagged for specific VLANs.

4. Summary:

The statement isTRUEbecause hybrid interfaces on a Layer 2 switch support traffic from multiple VLANs and allow flexible tagging configurations.

In RSTP, a port in thediscardingstate neither forwards data frames nor learns MAC addresses. A port in thelearningstate does not forward data frames but starts learning MAC addresses. Therefore, options A and B are correct, while C and D are incorrect due to misunderstandings of these states ​.

OptionA is false. When advertising a route to an IBGP peer, theBGP speaker does not modifythe AS_Path. It simply advertises the routeas-is, preserving the AS_Path learned from EBGP.

Clarification of the options:

Bis correct: When a route is sent to an EBGP peer, the local AS is prepended to the AS_Path.

Cis correct: The AS_Path begins with the local AS when a new route is advertised to an EBGP neighbor.

Dis correct: IBGP doesnotmodify AS_Path when passing routes within the same AS.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“BGP speakers prepend their AS number to the AS_Path only when advertising to EBGP peers. IBGP peers do not alter the AS_Path.”

(Chapter: BGP Path Attributes – Section: AS_Path)

BGP routes have a variety ofpath attributesthat describe their characteristics and influence route selection. These attributes include well-known mandatory attributes like AS-PATH and NEXT-HOP, as well as optional attributes like MED and LOCAL_PREF.

In Huawei devices, there is aHuawei-specific attributecalled"preference", which is a local parameter used to influence BGP route selection on the device.

Key Characteristics of "preference":

It is valid only locally on the router.

It is not shared with BGP peers.

It helps the router determine the best route when multiple routes exist for the same prefix.

It appears in the BGP routing table output in lowercase aspreference.

Thus, the correct answer ispreference(entered in lowercase as required).

 Edge Port Behavior

An edge port transitions directly to the Forwarding state but reverts to participating in RSTP calculations if it receives a valid configuration BPDU. Thus, statement C is false.

 HCIP-Datacom-Core Reference

The behavior of edge ports and their transitions are discussed in the RSTP enhancement sections​​.

 Understanding BGP Route Summarization:

In Border Gateway Protocol (BGP),route summarizationis a technique used to aggregate multiple specific prefixes into a broader summary prefix. This reduces the size of routing tables and improves routing efficiency.

Summarization helps to hide unnecessary details from other parts of the network while still maintaining connectivity.

HCIP-Datacom-Core Technology Training Material (BGP Route Summarization)​​.

 Suppressing Specific Routes:

When summarizing routes, thesuppress-spec-map keywordis used to suppress specific prefixes so that only the summarized route is advertised.

The suppressed routes are not advertised to BGP peers; instead, only the summary route is propagated.

A stateful inspection firewall tracks the state of active connections. If a packet matches an existing session in the firewall's state table, it is allowed to pass. The diagram indicates that the TCP packet matches the session state, so the firewall forwards it ​.

 ACL Number Ranges

Basic ACLs: Numbered from 2000 to 2999.

Advanced ACLs: Numbered from 3000 to 3999.

Layer 2 ACLs: Numbered from 5000 to 5999.

User-defined ACLs: Numbered from 4000 to 4999.

 HCIP-Datacom-Core Reference

ACL classifications and their number ranges are covered in the ACL principles and configuration chapters​​.

RPF (Reverse Path Forwarding) checks are used to prevent multicast loops. An RPF check uses theunicast routing table(ormulticast static routes, if configured) to determine the correct incoming interface for a multicast packet.

Multicast protocols like PIM use the RPF mechanism, and the unicast routing table is the primary reference.

Multicast dynamic routing protocolsdo not maintain their own separate tablesfor RPF by default.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“RPF checks are performed using the unicast routing table or multicast static routes. The interface through which the multicast source is reachable is considered valid for RPF.”

(Chapter: Multicast – Section: RPF Principle)

IGP routes can be injected into BGP using multiple methods, not just thenetworkcommand. Theimport-routecommand can also be used to redistribute IGP routes into BGP. Thenetworkcommand requires the route to exist in the routing table, whileimport-routeallows direct redistribution ​.

 DIS and DR Election

The IS-IS Designated Intermediate System (DIS) is responsible for generating and updating pseudonode LSPs on a broadcast network.

Unlike OSPF DR, the IS-IS DIS does not preempt by default. This behavior avoids unnecessary flapping in the network due to frequent DIS re-elections.

 HCIP-Datacom-Core Reference

The characteristics of DIS and DR behavior are explained in IS-IS network operation chapters​​.

Comprehensive and Detailed Step-by-Step Explanation:

Overview of IGMP Versions:

IGMPv1:The simplest version, supports basic group membership management using Report messages but lacks Leave messages.

IGMPv2:Adds features like Leave messages and Group-Specific Queries.

IGMPv3:Supports specifying multicast sources for Source-Specific Multicast (SSM).

Feature Supported by All Versions:

Report messagesare fundamental to IGMP functionality and are supported in all three versions.

Features Not Supported by All Versions:

Group-Specific Queries (A):Supported in IGMPv2 and IGMPv3.

Leave Messages (B):Introduced in IGMPv2.

Specifying Multicast Sources (D):Introduced in IGMPv3.

Comprehensive and Detailed Step-by-Step Explanation:

Switch Stack Overview:

In a switch stack, roles are assigned asmaster,standby, andslave.

The master handles configuration and control, while the standby serves as the backup master.

Behavior During Master Restart:

D:If the master switch restarts, the standby switch immediately takes over as the new master.

B:After the original master switch restarts, it becomes the master again (default behavior).

Incorrect Options:

A:The slave switch is not promoted to standby before the master switch restart completes.

C:The original standby switch remains the master after the restart.

On Huawei devices, multiple BGP processes can be configured on the same router, but they are typically used for specific use cases such as multi-instance deployments or virtual routers. This flexibility is supported by Huawei's routing protocols ​.

A stateful inspection firewall tracks the state of network connections and only matches the initial packet against its rule set. Subsequent packets in the same connection are matched in the statetable. Contrary to this, UDP packets can be inspected by correlating them with connection states, and packets in a single connection are always correlated ​.

 GRE Characteristics

GRE doesnotinherently support encryption or authentication. It is a tunneling protocol for encapsulating packets, and data security features must be implemented using other protocols such as IPsec.

Other correct attributes of GRE include:

B.Supports multicast transmission.

C.Acts as a Layer 3 VPN encapsulation technology.

D.Can work with VPN protocols like IPsec for better security.

 HCIP-Datacom-Core Reference

GRE features and limitations are discussed in VPN encapsulation technology chapters​​.

When a Huawei firewall receives a packet that does not match any existing session table entry, it discards the packet. This is part of the default firewall policy, which ensures that unrecognized traffic is treated as a potential security risk and blocked. This behavior is vital for preventing unauthorized access and mitigating external attacks. The feature aligns with Huawei's default security strategies as detailed in their firewall operation manuals ​.

In OSPF,Database Description (DD) packetsare used during the database synchronization process. In the first DD packet a router sends during neighbor establishment, three control bits are set:

I bit (Initial)= 1 → This indicates that the DD packet is the first in the sequence.

M bit (More)= 1 → This means more DD packets will follow.

MS bit (Master/Slave)= 1 → Set by the router assuming the master role in the exchange process.

Setting all three bits to 1 is a standard part of the DD exchange initiation.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“In the initial DD packet, the I, M, and MS bits are set to 1 by the master router initiating database exchange.”

(Chapter: OSPF Operation Mechanism – Section: Neighbor State Machine)

OSPF supports both area-level and interface-level authentication. When both are configured, interface authentication takes precedence over area authentication. This hierarchy ensures that specific interface-level configurations override the broader area-level settings when applicable ​.

A is false– Thedefault value of Local_Pref is 100, not 0.

B is false–Local_Pref is not advertised to EBGP peers, it is only sent toIBGP peers.

C is correct– TheLocal_Pref value stays constantunless modified by a route-policy or filter.

D is correct–Higher Local_Pref values indicate preferred paths, so BGP prefers the path with the highest Local_Pref among multiple options.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“Local_Pref is used to select the best outbound path for traffic leaving the AS. It is only shared among IBGP peers and defaults to 100. The higher the value, the more preferred the route.”

(Chapter: BGP Path Attributes – Section: Local Preference)

Comprehensive and Detailed Step-by-Step Explanation:

IS-IS Three-Way Handshake:

IS-IS uses athree-way handshaketo establish neighbor relationships.

This process is applied on bothpoint-to-point (P2P)andbroadcastnetwork types to confirm bidirectional communication.

P2P Networks:

Routers directly exchange IS-IS Hello (IIH) packets to establish adjacency.

Broadcast Networks:

IS-IS also uses the three-way handshake on broadcast networks to ensure that the Designated Intermediate System (DIS) election and adjacency formation are correct.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding IGMP Version Compatibility:

IGMP (Internet Group Management Protocol) supports multiple versions, such as IGMPv1, IGMPv2, and IGMPv3.

A device running alater versionof IGMP is backward-compatible and can identify Report messages from earlier versions.

However, a device running anearlier versionof IGMP cannot recognize the newer features or formats of later IGMP versions.

2. Best Practice:

To avoid compatibility issues, the IGMP version configured on the switch should be thesame as or later thanthe version used by the member hosts in the network.

3. Why the Statement is TRUE:

The statement is correct because it describes the compatibility behavior of IGMP versions and advises setting the switch IGMP version appropriately.

 LSP Generation in IS-IS

IS-IS routers generate new Link State Packets (LSPs) under the following conditions:

Interface Status Changes: When IS-IS interfaces go up or down, the link state changes, triggering LSP updates.

Periodic Updates: IS-IS periodically regenerates LSPs to ensure link-state information remains synchronized across the network.

Interface Metric Changes: Any modification to interface costs results in a new LSP to reflect the updated cost in the network.

 Incorrect Option

C. Inter-area IP routes change is incorrect because IS-IS does not inherently differentiate between areas for LSP generation.

 HCIP-Datacom-Core Reference

IS-IS LSP generation rules are detailed in the IS-IS configuration and implementation chapters​​.

Explanation of IS-IS Packet Types and Synchronization Process:

In the given scenario, R2 requests LSPs from R1 to synchronize its Link State Database (LSDB). The following IS-IS packet types are involved in this synchronization process:

1. P2P IIH (Point-to-Point IS-IS Hello):

Purpose:Establishes and maintains IS-IS neighbor relationships.

Step:This packet is exchanged initially to detect and maintain the adjacency between R1 and R2.

2. PSNP (Partial Sequence Number PDU):

Purpose:Requests missing or outdated LSPs (Link State PDUs) from a neighbor to synchronize the LSDB.

Step:In this case, R2 sends a PSNP to R1 to request the missing or outdated LSP.

3. LSP (Link State PDU):

Purpose:Contains routing information and is used to update the LSDB.

Step:R1 sends the requested LSPs to R2 for synchronization.

4. CSNP (Complete Sequence Number PDU):

Purpose:Lists all LSPs in the sender's LSDB to help neighbors verify and request missing LSPs.

Step:R1 sends a CSNP during retransmission timeout to notify R2 of its LSPs.

When two BGP peers negotiate the Hold Time, the shorter value between the two configured Hold Time values is selected. This ensures compatibility and maintains the stability of the BGP session ​.

 Understanding Router ID and Its Role in OSPF:

In OSPF, the Router ID uniquely identifies a router within the OSPF domain. If two routers are configured with the same Router ID, it can lead to issues such as LSA conflicts and flapping. This is because the Router ID is used as a key in OSPF operations, including LSA generation and database synchronization.

HCIP-Datacom-Core Technology Training Material (OSPF Basics - Router ID and LSA Handling)​.

 Scenario Details:

Different Areas: Even if the two routers belong to different areas, the Router ID remains globally significant in the OSPF domain. This means that any duplication of Router IDs will confuse OSPF mechanisms.

ASBR (Autonomous System Boundary Router): When one of the routers is an ASBR, it generates Type 4 and Type 5 LSAs to describe external routes. These LSAs use the Router ID asan identifier. If another router in the network has the same Router ID, conflicts occur during LSDB synchronization.

IGMPv1 supports general queries but does not define a Leave message. IGMPv2 introduces the Leave message type, which allows hosts to notify routers when they wish to leave a multicast group, improving efficiency. These distinctions align with the functionality of IGMP versions ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Overview of BFD Optimization:

BFD (Bidirectional Forwarding Detection) is a protocol that provides rapid detection of link failures.

Optimizing BFD involves adjusting parameters to balance between detection speed and network stability.

2. Analysis of Each Statement:

Option A: After a high priority is configured for BFD packets, BFD packets are preferentially forwarded.

Correct (True Statement).

High priority ensures that BFD packets are not delayed or dropped under congestion, improving detection accuracy.

Option B: To quickly learn about the network status and performance requirements, you can set the interval for sending BFD packets to the minimum value.

Incorrect (False Statement).

Setting the interval to the minimum value can lead to excessive BFD session flapping, which may overload the network or cause instability. The interval should be configured based on network requirements and conditions, rather than set to the minimum.

Option C: On a live network, some devices switch traffic only when a BFD session changes to the Up state... configure a delay to compensate for the time difference.

Correct (True Statement).

This is a valid optimization to avoid issues caused by timing mismatches between BFD and routing protocols.

Option D: If a BFD session flaps, master/backup switchovers are frequently performed... set the WTR time.

Correct (True Statement).

The WTR (Wait to Restore) timer helps stabilize BFD by delaying session recovery after a flap, reducing the risk of frequent switchovers.

3. Summary:

The false statement isB, as setting the BFD packet interval to the minimum can destabilize the network.

Comprehensive and Detailed in-depth Step-by-Step Explanation:

To establish an OSPF neighbor relationship, the following conditions must be met:

The routers must share a common network segment.

Their Hello and Dead intervals must match.

Their OSPF network types must be compatible.

The IP subnet masks must match.

If two OSPF routers are ondifferent network segmentsand havedifferent subnet masks, one solution is to change the OSPFnetwork typetoPoint-to-Point (P2P)on both interfaces.

Point-to-Point (P2P):

In a P2P network type, OSPF ignores the subnet mask mismatch and establishes the neighbor relationship regardless of the network mask.

This is ideal for directly connected links between two routers.

NBMA (Non-Broadcast Multi-Access):

This network type is used for networks like Frame Relay or ATM, where a single physical interface connects to multiple neighbors.

It is not applicable to solving subnet mask mismatches for a single link.

P2MP (Point-to-Multipoint):

This type treats the link as multiple P2P links. It is mainly used in hub-and-spoke topologies.

While it can be configured to solve subnet mask mismatches, it is more complex and less commonly used compared to the P2P type.

Broadcast:

This type requires all routers on the same segment to agree on subnet masks, so it cannot resolve the subnet mask mismatch issue.

Therefore, the correct answer isA. Point-to-point.

 Non-Client Definition in IBGP

In an IBGP setup with a Route Reflector (RR), a non-client is an IBGP peer that is neither the RR itself nor its client.

Non-clients must establish fully meshed IBGP connections with all other non-clients and the RR because IBGP rules prohibit route propagation between non-clients without a direct connection.

 HCIP-Datacom-Core Reference

The behavior of non-clients in an RR topology is clearly outlined in the BGP implementation chapters​​.

A is correct– Confederations arespecifically designed for large-scale BGP deploymentswhere a full IBGP mesh is impractical.

B is correct– Sub-ASs within a confederation establishEBGP-like connectionsbetween each other but behave like IBGP within the overall AS. These sub-ASsdo not require full-mesh inside the confederation, but EBGP rules are followed between sub-ASs.

C is false–Not all devices need to be reconfigured. Devices within the same sub-AS retain normal IBGP behavior and minimal changes.

D is correct– Confederation istransparent to external peers, so thelogical topology remains the samefrom outside the AS.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“BGP confederation divides an AS into multiple sub-ASs. EBGP-like sessions are established between sub-ASs, while reducing IBGP mesh complexity. The external AS still sees the AS as one unit.”

(Chapter: BGP Scalability Enhancements – Section: Confederation)

Router LSAs (Type 1) and Network LSAs (Type 2) are advertised only within a single OSPF area, as they describe the topology within the area. In contrast, Summary LSAs (Type 3) and AS External LSAs (Type 5) are used for inter-area and external routing, respectively ​.

 IGMP:Manages IPv4 multicast group members and runs on the multicast network's last segment (that is, the network segment where a Layer 3 network device is connected to user hosts).

 PIM:Sends multicast data over the network to the multicast device that is connected to group members that have requested the multicast data, implementing multicast data forwarding based on routes.

 IGMP Snooping:Manages and controls the forwarding of multicast data packets to effectively suppress the flooding of multicast data packets on the Layer 2 network.

 IGMP (Internet Group Management Protocol):

IGMP is used by hosts and adjacent multicast routers to establish and maintain multicast group memberships on a local subnet.

It allows a host to inform a multicast router of its desire to receive multicast traffic for a specific group.

It operates at Layer 3 and runs on the last segment of the network.

HCIP-Datacom-Core Technology Training Material (Multicast Fundamentals)​.

 PIM (Protocol Independent Multicast):

PIM is a routing protocol designed for efficient routing of IP multicast traffic. It determines the paths over which multicast packets should be forwarded.

PIM is "protocol-independent" because it uses the underlying unicast routing table for RPF (Reverse Path Forwarding) checks.

It is responsible for distributing multicast data throughout the network.

In the PIM protocol,Register StopandGraftmessages are sent with unicast destination addresses, typically to specific neighbors or RP (Rendezvous Point) routers. Other messages likeBootstrapandAssertuse multicast addresses for broader dissemination across the network ​.

The election of a Designated Router (DR) and Backup Designated Router (BDR) occurs during the OSPF network's initial setup or upon the failure of an existing DR. A new router joining an OSPF network does not automatically preempt the current DR, even if it has the highest priority. DR and BDR elections are not preemptive. The other statements are correct regarding OSPF DR/BDR election processes ​.

Comprehensive and Detailed Step-by-Step Explanation:

Definition of the Origin Attribute:

The Origin attribute is a well-known mandatory attribute used to indicate the source of a route. It has three possible values:

i (IGP):The route was injected into BGP using the network command.

e (EGP):The route was learned from an EGP protocol (not commonly used now).

? (Incomplete):The route was redistributed into BGP from another routing protocol.

Analysis of Each Option:

Option A:Correct. When the network command is used, the Origin is set toi (IGP).

Option B:Incorrect. Routes learned from EGP have the Origin attribute set toe (EGP), not? (Incomplete).

Option C:Correct. BGP prefers routes with the Origin attribute in the order:IGP > EGP > Incomplete.

Option D:Correct. The Origin attribute is a well-known mandatory attribute.

ICMPv6 messages are classified into two types: error messages (e.g., Destination Unreachable, Time Exceeded) and informational messages (e.g., Echo Request, Echo Reply). This classification is fundamental to ICMPv6's operation ​.

Thesummary automaticcommand in BGP is used to enable automatic summarization of routes, particularly for classful networks. However, manual summarization takes precedence over automatic summarization when both are configured. This makes the statement claiming automatic summarization takes precedence false ​.

In the topology, SWB's GE0/0/2 is the Root Port because it has the least cost path to the Root Bridge (SWA). SWC's GE0/0/1 is the Designated Port because it forwards traffic to SWA while maintaining the shortest path to the Root Bridge. This setup ensures efficient traffic flow in the spanning tree topology ​.

BFD control packets are encapsulated in UDP packets, and the destination port number for multi-hop BFD control packets is 4784. This is a standardized port for multi-hop BFD operation ​.

ARP spoofing is a Layer 2 attack, as it targets ARP tables in switches or end devices. All other attacks, including IP spoofing, ICMP attacks, and Smurf attacks, are network layer (Layer 3) attacks ​.

 IS-IS Interface Types

IS-IS interfaces are categorized based on physical link characteristics:

Point-to-Point (P2P): Direct connections between two routers.

Broadcast: Shared medium networks where multiple routers communicate.

 Incorrect Options

C. P2MP and D. NBMA are not standard interface classifications in IS-IS.

 HCIP-Datacom-Core Reference

IS-IS physical link classifications are elaborated in IS-IS link configuration sections​​.

In SNMP (Simple Network Management Protocol), the MIB (Management Information Base) defines the attributes of a managed device. It acts as a structured database of managed objects, each described by a unique OID (Object Identifier). These objects provide critical information and control interfaces for network management. Other elements like the agent (manages the MIB) and NMS (queries the agent) do not define attributes but interact with the MIB ​.

Comprehensive and Detailed Step-by-Step Explanation:

ACL Capabilities:

ACLs are versatile tools that can match:

Data packets:Using IP addresses, protocols, ports, etc.

Routes:ACLs can be used in route filtering, matching both IP prefix length and mask length.

Correct Statement:

ACLs can matchboth the IP address prefix length and mask lengthin route filtering applications.

 BGP Open Message Components

The Open message contains the following critical parameters:

Local AS Number: The autonomous system of the router.

Router ID: A unique identifier for the router.

Hold Time: The maximum time the router will wait for Keepalive or other messages from its peer.

 Incorrect Option

C. NLRI: Network Layer Reachability Information is not included in Open messages; it is carried in Update messages.

 HCIP-Datacom-Core Reference

The structure and contents of Open messages are explained in BGP protocol details​​.

 BGP Route Flapping and Mitigation

While route flapping is a concern in large-scale networks, BGP employs mechanisms such asRoute Dampeningto mitigate its impact. Route dampening suppresses frequently flapping routes for a period of time to reduce resource consumption and network instability.

Therefore, it is incorrect to state that the issue cannot be resolved in BGP.

 HCIP-Datacom-Core Reference

The mechanism of route dampening is detailed in the BGP optimization chapters​​.

By default, Huawei firewalls create security zones nameduntrust,dmz,trust, andlocal. These zones facilitate security policies for inbound, outbound, and inter-zone traffic control ​.

Multi-channel protocols such as H.323 and FTP use separate control and data channels. H.323 uses different channels for call signaling and media streaming, while FTP uses a control channel for commands and a data channel for file transfers. Telnet and SMTP are single-channel protocols ​.

Routing policies are used to control how routes are imported, advertised, or received. Policy-Based Routing (PBR) is used to forward packets based on policies, bypassing the routing table. Routing policies are not used for packet forwarding ​.

By default, a router interface sends PIM (Protocol Independent Multicast) Hello messages every 30 seconds to maintain neighbor relationships. This interval can be adjusted using configuration commands ​.

In PIM-DM (Protocol Independent Multicast - Dense Mode), the SPT (Shortest Path Tree) establishment process involves flooding to propagate multicast traffic across the network, prune messages to stop sending multicast traffic to unwanted interfaces, and graft messages to re-establishforwarding when needed. State-refresh is not directly involved in SPT establishment but helps maintain the prune state ​.

Comprehensive and Detailed Step-by-Step Explanation:

Bidirectional Forwarding Detection (BFD):

BFD is a lightweight protocol that provides rapid fault detection on links independent of the underlying routing protocol or media.

Requirements for BFD:

Both devices at the endpoints of the link must support and configure BFD for it to operate.

If one device does not support BFD, the feature cannot be used for link detection.

In BGP and other TCP-based protocols like OSPF and IS-IS, when devices havedifferent Hold Times, thesmaller value is chosenafter negotiation. This ensuresfaster detectionof communication loss.

The Keepalive and Hold Timers are negotiated during the establishment of a BGP session.

The smaller Hold Timeis used to maintain symmetry and prevent timeouts.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“When negotiating Hold Time, both ends agree to use the smaller of the two values. This value is used to detect failures faster.”

(Chapter: BGP Fundamentals – Section: BGP Session Establishment)

Comprehensive and Detailed Step-by-Step Explanation:

Portal Authentication:

Portal authentication uses a web-based mechanism where clients are redirected to a login page.

Communication between the access device and Portal server uses HTTP or HTTPS protocols.

Correct Statements:

Option A:HTTP or HTTPS is used for Portal authentication.

Option D:Portal protocol packets are transmitted overTCPfor reliable communication.

Incorrect Statements:

Option B:Port 2000 is not the default for processing Portal packets.

Option C:The default destination port for communication with the Portal server is not 50100.

The IPv6 address 2001:0DBB:B8:0000:C030:0000:0000:09A0:CDEF can be compressed by removing leading zeros in each segment and collapsing consecutive zero groups into ::. The result is 2001:DBB:B8:0:C030::9A0:CDEF ​.

The output shows that the router with the IP10.0.12.2is the Backup Designated Router (BDR), as indicated in theState: BDRfield. The router ID is10.0.2.2, the interface cost is 1, and the IP address of the interface is10.0.12.2. Hence, C is the correct answer ​.

The route-policy configuration specifies that node 10 matches the IP prefix11.1.0.0/16and applies a cost of 300 to this route. Once a route matches a node, it is no longer processed by subsequent nodes, making option D incorrect. Option B is also incorrect because only specific matching routes have their costs changed ​.

Let’s analyze the process step-by-step:

R1redistributes thedirect route 10.1.1.0/24intoOSPF.

This OSPF route reachesR2andR3.

R2 and R3 are in an environment that usesIS-IStowardsR4.

BothR2 and R3 re-advertisethis OSPF route into IS-IS toward R4 (bidirectional route redistribution).

OnR3, aroute-policy named hcipis applied to controlASE (Autonomous System External) route preference.

The ACL matches the route10.1.1.0/24.

The route-policy sets thepreferenceof this ASE route to14.

InHuawei VRP, if a route-policy applied via preference ase route-policy matches a route, itmodifies the preferencevalue of the redistributed route when it is advertised.

By default:

OSPF ASE routeshave apreference of 150.

But in this case, due to the policy applied, the preference is explicitly changed to14on R3 before re-advertising to R4.

So,R4will install the route10.1.1.0/24from R3 withpreference 14, assuming R2 doesn’t provide a better preference.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“You can control the preference of OSPF ASE routes by using a route-policy and applying it with the command preference ase route-policy. When the policy matches, the specified preference is used instead of the default (150).”

(Chapter: OSPF Advanced Features – Section: Route Control and Inter-AS Route Redistribution)

The provided BGP error display shows the error timestamp as12:40:39 on March 22, 2010. The error message confirms a mismatch in the peer AS number, as indicated in the "Incorrect remote AS" error info. This eliminates options related to other causes, and the timestamp in Option A is incorrect ​.

Understanding DIS Election in IS-IS:

On an IS-IS broadcast network, aDesignated Intermediate System (DIS)is elected to create and update pseudonodes for efficient communication.

The election is based on the following criteria:

DIS Priority:The router with the highest priority is elected as the DIS.

Router ID (tie-breaker):If priorities are equal, the router with the highest Router ID is elected.

Analyzing the DIS Priorities and Router IDs:

R1: Priority = 64, Router ID = 1.1.1.1

R2: Priority = 1, Router ID = 2.2.2.2

R3: Priority = 127, Router ID = 3.3.3.3

R4: Priority = 10, Router ID = 4.4.4.4

Among the routers,R3 has the highest DIS priority (127), making it the DIS.

Correct Option:

Option B (R3):Correct, as R3 has the highest priority.

Option A (R1):Incorrect, as its priority is lower (64).

Option C (R4):Incorrect, as its priority is lower (10).

Option D (R2):Incorrect, as its priority is the lowest (1).

A stateful inspection firewall tracks the state of network connections and only matches the initial packet against its rule set. Subsequent packets in the same connection are matched in the state table. Contrary to this, UDP packets can be inspected by correlating them with connection states, and packets in a single connection are always correlated ​.

The correct command for configuring the VRRP (Virtual Router Redundancy Protocol) preemption delay isvrrp vrid 1 preempt-delay 20. This command sets the delay before a higher-priority VRRP router preempts the master role, ensuring stable operation during network transitions ​.

From the command output, the interface S4/0/0 has its cost value explicitly listed under theCostsection as 20 for Level-1 circuits. This means that all traffic routed through this interface will incur this cost in the IS-IS metric calculation. The other options (such as circuit level and IPv6 support) are either not correct or not supported by the provided output ​.

Option B isfalse. By default, when the aggregate command is usedwithout any options, BGP generates asummary route, andsuppresses the specific routesthat fall under that summary. To advertise both specific and summary routes, you mustexplicitly configurethe detail-suppressed option to control whether specifics are suppressed or not.

Explanation of the other options:

Ais correct: When suppress-policy is specified, only specific routes matching the policy are advertised; others are suppressed.

Cis correct: The summary automatic command causes summarization based on classful boundaries, which is a legacy behavior.

Dis correct: With detail-suppressed, only the summary route is advertised, not specific prefixes.

Reference from Huawei HCIP-Datacom-Core Technology Study Guide:

“The aggregate command suppresses specific routes by default unless explicitly configured otherwise. Use of suppress-policy or detail-suppressed allows control over which routes are advertised.”

(Chapter: BGP Advanced Features – Section: Route Aggregation)

LS Ack (Link State Acknowledgment) packets are used to acknowledge received LSAs and do not contain complete LSA information. Instead, they contain only the headers of LSAs being acknowledged. This contrasts with LS Update packets, which carry full LSA details. The misunderstanding of LS Ack functionality makes this statement false ​.

 ACL Matching in Huawei Routers:

Access Control Lists (ACLs) are used to filter packets based on specific criteria, such as source/destination IP, ports, or protocols.

When a packet arrives, the Huawei router processes it against the configured ACL rules to decide whether to permit or deny the packet.

Comprehensive and Detailed Step-by-Step Explanation:

iMaster NCE-Campus Overview:

iMaster NCE-Campus is Huawei’s network management platform for managing and controlling campus networks.

It supports user authentication, including STA (Station) authentication, in WLAN environments.

Authentication Modes Supported:

iMaster NCE-Campus integrates with AAA (RADIUS) servers to perform authentication for wireless clients.

Correct Statement:

The platform can function as an authentication server for WLAN STAs.