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

Comprehensive and Detailed Step-by-Step Explanation:

HSB (Hot Standby Backup) Service:

HSB is used on WLAN controllers to back up critical information in real time to a backup device, ensuring service continuity in case of failures.

Backed-Up Information:

CAPWAP Tunnel Information (A):Essential for maintaining connections between APs and controllers.

AP Entries (C):Information about connected APs is backed up.

User Data Information (D):Includes client authentication and session details.

Incorrect Option:

DHCP Address Information (B):Not part of HSB's responsibilities, as DHCP is handled separately.

 GMP Snooping Proxy

IGMP snooping proxy allows the switch to substitute for upstream Layer 3 devices and downstream hosts, reducing unnecessary bandwidth consumption by consolidating IGMP messages.

 HCIP-Datacom-Core Reference

The IGMP snooping proxy functionality is described in multicast optimization and IGMP configuration chapters​​

Comprehensive and Detailed In-Depth Explanation:

A. TRUE→ Ifpreemption is enabled, ahigher-priority routercan take over as theMaster.

B. TRUE→ Ifpreemption is disabled, thecurrent Master remains activeeven if a higher-priority router joins.

C. TRUE→ TheMaster router sends VRRP Advertisement packetsto maintain its role.

D. FALSE→ If aVRRP router is the IP address owner, itautomatically becomes the Masterwithout needing toparticipate in an election.

????Reference:Huawei HCIA-Datacom Study Guide, VRRP Priority and Preemption Mechanisms.

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 ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding the IGMP Group Entry:

The IGMP group entry contains key information about multicast groups on the interface:

Group Address (225.1.1.2):The multicast group address that the user has joined.

Last Reporter (10.1.6.10):The IP address of the last host that sent an IGMP Report message for this group.

Uptime:The duration since the group was first reported.

Expires:The remaining time before the group entry ages out if no further reports are received.

2. Analysis of Each Statement:

Option A: This entry can be used to construct the corresponding (S, G) entry.

Incorrect.

This is a group entry for IGMP, which contains information about the group (G) but does not include a specific source (S). (S, G) entries are created in PIM (Protocol Independent Multicast), not IGMP.

Option B: This entry is created when the device receives an IGMP Join message from a user.

Correct.

IGMP Join messages are used by hosts to signal their intent to join a multicast group. When such a message is received, the group entry is created.

Option C: Expires indicates the aging time of the IGMP group.

Correct.

The "Expires" field shows the remaining time before the group entry ages out if no further IGMP reports are received.

Option D: 225.1.1.2 is the address of the group that the user joins.

Correct.

The "Group Address" field explicitly states that 225.1.1.2 is the multicast group that the user has joined.

3. Summary:

Correct Options:B, C, D

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 ​.

Comprehensive and Detailed In-Depth Explanation:

OSPF usesHello packetsto establish and maintain neighbor relationships. The method of sending Hello packets depends on thenetwork type:

Broadcast networks(e.g., Ethernet) usemulticast (224.0.0.5)to discover and maintain OSPF neighbors.

Point-to-Point (P2P) networks(e.g., PPP links) also usemulticast (224.0.0.5)for Hello packet exchange.

Non-Broadcast Multi-Access (NBMA) networks(e.g., Frame Relay) requiremanual neighbor configurationand useunicast Hello packetsinstead of multicast.

Point-to-Multipoint (P2MP) networkscan send Hello packetseither unicast or multicast, but it depends on configuration.

????Reference:Huawei HCIA-Datacom Study Guide, OSPF Neighbor Discovery and Hello Packet Mechanism.

In a route-policy, attributes such asMED(Multi-Exit Discriminator) andLocal-Preferencecan be used in apply clauses to influence BGP route selection. Attributes likeAS_PathandTagare typically matched or filtered but not directly applied in the apply clause ​.

The Forwarding Information Base (FIB) is derived from the router's routing table and contains the exact forwarding entries used to route packets. It directly guides packet forwarding decisions by matching incoming packets with the correct output interface or next-hop address ​.

An IP prefix filter is designed to match both the IP address and its prefix length, making it suitable for filtering routing information rather than data packets. Options A and D are incorrect because IP prefix filters do not work directly on data packets, and they can match both prefix numbers and lengths ​.

In Layer 3 roaming scenarios, STAs (stations) remain on different subnets before and after roaming. To ensure that user traffic reaches the original subnet, it must be tunneled back over a CAPWAP tunnel. This technique prevents disruptions in communication and enables seamless roaming. Huawei’s Layer 3 roaming design guidelines emphasize the use of CAPWAP tunnels for user traffic forwarding ​.

 R3, as the DIS in the Level-2 domain, periodically sends Complete Sequence Number Protocol Data Units (CSNPs) to ensure LSDB synchronization among Level-2 routers.

 R1 and R2 are in a Level-1 domain, and IS-IS requires the receiving router (R2) to acknowledge an LSP from R1 by sending a Partial Sequence Number Protocol Data Unit (PSNP).

 IS-IS LSPs in a broadcast network are sent using multicast, not unicast, making option C incorrect.

 For Level-2 LSPs, acknowledgments are not provided using PSNP by R3; CSNPs are sufficient for synchronization ​.

When configuring VRRP, the virtual router priority and virtual IP address are mandatory because they define the VRRP instance and its role within the group. Preemption mode and preemption delay are optional configurations that influence how routers take over the master role when priorities change. These are not mandatory for the VRRP protocol to function ​.

According to BGP route selection rules, a higherLocal_Prefvalue indicates a more preferred route. This rule is used to influence traffic flow within an autonomous system (AS), giving preference to routes with a higherLocal_Preffor outgoing traffic ​.

Comprehensive and Detailed Step-by-Step Explanation:

WAN Definition:

A WAN is a large-scale network spanning a wide geographical area, connecting smaller networks such as LANs and MANs.

Use Cases:

WANs are commonly used for interconnecting campus networks, branch offices, and data centers over long distances.

Correct Statement:

The statement accurately describes the purpose and scope of WANs.

Comprehensive and Detailed Step-by-Step Explanation:

Distance-Vector Protocols:

Distance-vector protocols determine the best path based on the distance to a destination and periodically share the entire routing table with neighbors.

Example:RIPis a distance-vector protocol.

Link-State Protocols:

Link-state protocols share information about directly connected links, enabling routers to build a complete map of the network.

OSPF(Open Shortest Path First) andIS-IS(Intermediate System to Intermediate System) are link-state protocols that use Dijkstra’s algorithm to calculate the shortest path.

Border Gateway Protocol (BGP):

BGP is neither a distance-vector nor a link-state protocol. Instead, it is classified as apath-vector protocolthat selects the best path based on attributes such as AS-path, next-hop, and local preference.

 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:

STP and RSTP Behavior:

STP:Only thedesignated portprocesses inferior BPDUs. Inferior BPDUs are received from downstream switches and typically indicate topology changes.

RSTP:All ports, regardless of role (root, designated, or alternate), process inferior BPDUs to ensure faster convergence.

Behavior Difference:

RSTP improves convergence by allowing any port to process inferior BPDUs, unlike STP, which restricts this function to designated ports.

Explanation of VLAN Pool Assignment Algorithms:

In WLANs,VLAN poolshelp reduce broadcast domains and improve network performance by distributing users across multiple VLANs. Two algorithms are used for VLAN assignment:

Even Assignment Algorithm:

The number of users in each VLAN is even.

This algorithm assigns users evenly across VLANs, ensuring a balanced distribution of users in each VLAN.

When STAs go offline and online again, their VLANs and IP addresses may easily change.

Since the assignment is based on maintaining even distribution, a device (STA) may not be assigned the same VLAN when it reconnects, leading to potential IP address changes.

Hash Assignment Algorithm:

The number of users in each VLAN is uneven.

The hash algorithm assigns users to VLANs based on a hash value (e.g., derived from the MAC address). This may result in an uneven distribution of users across VLANs.

VLANs and IP addresses remain unchanged for STAs that go offline and online again.

The hash algorithm ensures that a device reconnects to the same VLAN, preserving its IP address.

A screenshot of a computer Description automatically generated

Secure access channels include protocols that encrypt the transmitted data to protect against interception or unauthorized access. HTTPS (HyperText Transfer Protocol Secure) ensures data encryption over web communications, while SFTP (Secure File Transfer Protocol) provides secure file transfer by utilizing SSH for data encryption. Telnet and SNMPv2, on the other hand, lack robust encryption and are considered insecure. Huawei security standards highlight the importance of encrypted communication to prevent data leaks ​.

A is correct– Local attack defense can classify and prioritize packets (e.g., OSPF, BGP, SSH) andensure critical protocols are processed firstby the CPU.

B is correct– Thedynamic link protection functionensures session-based applications (like SSH)are not disruptedeven during a CPU attack.

C is false– Different protocols havedifferent importance levels, soindividual rate limitsshould be configured, not a uniform one.

D is correct– CPU protectionalso applies to management interfaces, such as those used for Telnet, SSH, or SNMP.

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

“Devices support local attack defense by classifying packets, setting priorities, and limiting rates to protect CPU resources. These policies also apply to the management interface.”

(Chapter: Network Security – Section: Local Attack Defense)

The command output indicates that the OSPF neighbor state isFulland that the neighbor relationship has been established. The statement confirms that the negotiation process during the exchange of DD (Database Description) packets has determined the role of the router, with the local device becoming the slave in the Master-Slave relationship, which is critical for LSA synchronization. The other options do not align with the output or OSPF principles ​

The scenario describes a mismatch in OSPF network types between two connected routers: one set to Point-to-Point (P2P) and the other set to Point-to-Multipoint (P2MP). While aligning Hello intervals may seem sufficient for establishing an OSPF neighbor relationship, the fundamental mismatch in network types introduces issues.

OSPF Network Types

P2P: Assumes a direct connection with a single neighbor, uses faster convergence and simpler LSDB synchronization.

P2MP: Supports multiple neighbors on a single interface, requiring different handling for DR/BDR roles and LSDB updates.

Impact of Network Type Mismatch

If Hello intervals are aligned, adjacency establishment might occur. However, mismatched network types affect neighbor role assignment and LSDB synchronization.

P2P expects a direct link and would handle updates differently than P2MP, which assumes multiple neighbors. This leads to inconsistencies in route calculation and forwarding.

HCIP-Datacom-Core Reference

OSPF Basics and Configuration​clearly outlines the criticality of consistent network type configuration for stable OSPF operation.

Lab examples in the HCIP Datacom Lab Guide​further demonstrate the consequences of such mismatches, including unstable neighbor states and incomplete LSDB synchronization.

Hence, the statement that neighbor relationships and LSDB synchronization remain unaffected is incorrect. Proper OSPF operation requires matching network types in addition to aligned Hello intervals.

Comprehensive and Detailed Step-by-Step Explanation:

BGP ConnectRetry Timer:

The ConnectRetry timer is used when establishing a TCP connection between BGP peers.

If the connection is successful, the timer is disabled.

If the connection fails, the timer restarts, and the router attempts to reconnect after the timer expires.

Behavior:

This timer prevents excessive connection attempts and ensures efficient resource utilization.

In the given topology, the route from R4 to 10.0.2.2/32 traverses R3, which performs route leaking from Level-2 to Level-1. The cost is calculated as follows: R4 to R3 (40) + R3 to R2 (10) + R2 to the destination (30), resulting in a total cost of 80 ​.

By default, Huawei firewalls create security zones such as Trust, Untrust, and Local. The DMZ (Demilitarized Zone) is a security zone explicitly created by users. A DMZ is used to isolateaninternal network from the external one, providing an additional layer of security by placing public-facing services (e.g., web servers) in this intermediary zone. This setup ensures that if a public-facing service is compromised, the internal network remains secure. Huawei Firewall configuration steps confirm this zoning principle, making DMZ creation an explicit user-driven action ​.

In Huawei firewalls, the security level of a zone can be reconfigured by an administrator, making the statement that it cannot be changed false. Other statements accurately describe security level restrictions or defaults ​.

Comprehensive and Detailed Step-by-Step Explanation:

Analysis of the OSPF Neighbor State:

Router ID 10.0.5.5:

On interface 10.0.235.2 (GigabitEthernet0/0/1), the neighbor state is Full, indicating that adjacency is established.

The Designated Router (DR) is 10.0.235.5, which is the same as the neighbor's address.

Router ID 10.0.4.4:

On interface 10.0.24.2 (Serial1/0/1), the neighbor state is also Full, meaning adjacency is established.

The DR/BDR election status shows None, indicating that the interface is on a point-to-point link where DR/BDR election does not apply.

Validation of Each Option:

Option A: Correct. The DR IP address is explicitly shown as 10.0.235.5.

Option B: Correct. The neighbor state for both 10.0.5.5 and 10.0.4.4 is Full, confirming adjacency is established.

Option C: Incorrect. DR/BDR elections are irrelevant on point-to-point links like Serial1/0/1.

Option D: Correct. The Router IDs of R2's neighbors are explicitly listed as 10.0.5.5 and 10.0.4.4.

 ACL Modification

Named ACLs can be modified after their creation. Unlike numbered ACLs, named ACLs provide greater flexibility for editing individual rules without deleting the entire ACL.

Therefore, the statement is incorrect.

 HCIP-Datacom-Core Reference

The flexibility and editability of named ACLs are discussed in the ACL configuration sections​​.

Thesilent-interfacecommand disables the sending of OSPF packets, including Hello packets, on the specified interface, which prevents the establishment of OSPF neighbor relationships. However, the interface can still advertise directly connected routes through other interfaces, making Option C incorrect ​.

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

TheNetwork Entity Title (NET)is a unique identifier assigned to an IS-IS router. It is derived from theNetwork Service Access Point (NSAP)address and consists of the following components:

Area Address:

Identifies the area in which the router resides.

Multiple routers in the same IS-IS area must have the same area address.

System ID:

Uniquely identifies the router within the IS-IS area.

The System ID is typically derived from the router's loopback IP address or another unique value.

SEL (Selector Field):

The SEL field is always set to00for IS-IS NETs.

The NET is used by IS-IS for route calculation and to identify the router within the IS-IS domain. Therefore, the statement isTRUE.

Comprehensive and Detailed Step-by-Step Explanation:

Blackhole Route Issue in BGP:

In IBGP, the next hop of a route learned from an EBGP peer is not changed by default. If an IBGP peer cannot reach the next hop, blackhole routes may occur.

To prevent this, thepeer next-hop-localcommand is used to set the next hop to the local router's IP address.

Other Commands:

peer mpls-local-ifnet:Used in MPLS networks to set the next hop as the local interface address.

peer private-nexthop:Allows advertising private IP addresses as the next hop.

peer next-hop-invariable:Ensures the next hop is not modified during route advertisement, which is the opposite of what is required here.

TheOriginattribute in thedisplay bgp routing-tableoutput is marked asi, indicating that the route was injected into the BGP routing table using thenetworkcommand. The other options are incorrect because the AS path is not displayed, the MED is0, and the route is marked as the best (>), meaning it is the optimal route ​.

After Layer 3 roaming, the STA’s traffic is forwarded from the Foreign AP (FAP) to the Foreign AC (FAC), and then to the Home AC (HAC) before reaching the upper-layer network. This ensures that the STA remains on the same subnet without breaking existing sessions ​.

AI-driven networks focus on maximizing efficiency by minimizing latency to enhance data processing and decision-making speed. The AI era emphasizes leveraging large data volumes and ensuring rapid data center interconnectivity. This makes low latency a critical requirement for AI-ready data center networks, as highlighted in Huawei's AI and data center network optimization materials ​.

Comprehensive and Detailed Step-by-Step Explanation:

Single-Hop BFD:

Single-hop BFD is used for detecting link failures in directly connected devices.

It usesUDP port 3784for communication.

Multi-Hop BFD:

For multi-hop scenarios, BFD usesUDP port 4784to ensure end-to-end connectivity.

Incorrect Options:

TCP ports 3784 and 4784 (C and D):BFD does not use TCP.

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)

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 ​.

Comprehensive and Detailed Step-by-Step Explanation:

Route Policy Overview:

Aroute-policyis a policy-based routing tool that filters and modifies routing information.

It consists of one or morenodes, and each node can specify match conditions and apply actions to routes.

Maximum Number of Nodes:

The maximum number of nodes supported in a route-policy is1024, allowing flexibility in route filtering and control.

Route summarization in OSPF is restricted to specific routers: Area Border Routers (ABRs) and Autonomous System Boundary Routers (ASBRs). These devices perform summarization to reduce routing table size and minimize advertised routing information between areas or across AS boundaries. Regular routers cannot perform route summarization, making this statement false ​.

Configuration Analysis:

OnR2, the following configuration has been applied:

acl 200

rule deny source 10.1.0.0 0.0.3.0

rule permit

#

ospf 1

filter-policy 2000 import

This configuration usesACL 200to filter routes during import into the OSPF routing table on R2.

Rule deny source 10.1.0.0 0.0.3.0:Blocks routes in the range10.1.0.0/24 to 10.1.3.0/24(inclusive).

Rule permit:Allows all other routes to be imported.

Impact of ACL 200 on Route Import:

10.1.0.0/24 to 10.1.3.0/24:These subnets are explicitly denied by ACL 200 and will not appear in R2's routing table.

10.1.4.0/24 and beyond:These subnets are permitted by therule permitstatement and will be imported into R2's routing table.

Routing Table Entries on R2:

Option A (10.1.4.0/24):Exists in R2's routing table because it is permitted.

Option B (10.1.3.0/24):Does not exist because it is denied by ACL 200.

Option C (10.1.2.0/24):Does not exist because it is denied by ACL 200.

Option D (10.1.1.0/24):Does not exist because it is denied by ACL 200.

A (10.1.4.0/24)

The CAPWAP heartbeat detection interval is typically multiplied by a predefined factor to determine the switchover time. For instance, in Huawei devices, a common default is three missed heartbeats before a switchover is triggered. With a detection interval of 20 seconds, the switchover occurs after 60 seconds (20 x 3). This ensures that transient network issues do not cause unnecessary switchovers ​.

Comprehensive and Detailed In-Depth Explanation:

OSPF-to-BGP route redistributiondoesnot allow modification of MED valuesdirectly using aroute-policyin Huawei devices.

Instead,MED can be set using a BGP attribute policy, not through the import command.

All other options (B, C, D) are correct:

B→ Route-policycan filter imported direct routes.

C→ network commanddoes not modify attributes, only announces existing routes.

D→ peer commandcan set Local Preferencevia route-policy.

????Reference:Huawei HCIA-Datacom Study Guide, BGP Route Policy and Attribute Modification.

Attributes such ascommunity,tag, andorigincan be directly referenced in theapplyclause of a route-policy. However,IP-prefixis not an attribute but a prefix list used for matching, and it cannot be directly applied ​.

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)

Comprehensive and Detailed In-Depth Explanation:

NET (Network Entity Title)is a special form ofNSAP (Network Service Access Point)used inIS-IS routing.

NET consists of three fields:

AFI (Authority and Format Identifier) + IDI (Initial Domain Identifier) + Area Address→ Identifies thearea.

System ID→ Uniquely identifies arouter within an area(similar to an OSPF Router ID).

SEL (NSEL - N-selector)→ Always0in a NET, as IS-IS operates at Layer 3.

SinceSystem IDuniquely identifies ahost/router within an area, the correct answer isA.

????Reference:Huawei HCIA-Datacom Study Guide, IS-IS Addressing and NET Structure.

Comprehensive and Detailed Step-by-Step Explanation:

Routing Table Structure:

Routers maintain a localcore routing tableand separateprotocol routing tablesfor OSPF, BGP, etc.

The local core routing table storesoptimal routesselected based on metrics, protocol preferences, and administrative distances.

Fields in the Core Routing Table:

Destination Address (A):Indicates the destination network or host.

Routing Protocol Preference (B):Determines the priority of routing protocols (e.g., OSPF > RIP).

Routing Protocol (D):Specifies the protocol (e.g., OSPF, BGP) that contributed the route.

Inbound Interface:This is stored in the protocol-specific routing table but not in the local core table.

Comprehensive and Detailed Step-by-Step Explanation:

OSPF Route Preference Hierarchy:

OSPF uses the following preference order for route types when the prefix is the same:

Intra-area routes (D): Routes within the same OSPF area have the highest priority.

Inter-area routes (B): Routes between different OSPF areas are preferred after intra-area routes.

Type 1 external routes (A): External routes redistributed into OSPF, considering the internal OSPF cost to the ASBR.

Type 2 external routes (C): External routes redistributed into OSPF, ignoring the internal OSPF cost to the ASBR.

Lowest Priority:

Type 2 external routes (C) are given the lowest priority because they represent external information that does not consider internal OSPF costs.

Inasynchronousmode, the local device sends BFD control packets at predefined intervals, and the remote device monitors the receipt of these packets to detect connectivity issues. This is one of the two operating modes in BFD, the other beingdemandmode ​.

Comprehensive and Detailed In-Depth Explanation:

Spanning Tree Protocol (STP)haslong convergence timesdue toListening and Learning states.

Rapid Spanning Tree Protocol (RSTP)introduces:

Proposal/Agreement (P/A) mechanism→ Allows ports to quickly transition toForwarding statewithout waiting.

This mechanism significantlyreduces convergence timein aswitched network.

Since RSTPdoes use the P/A mechanismto accelerate port forwarding, the statement istrue.

????Reference:Huawei HCIA-Datacom Study Guide, STP vs. RSTP and P/A Mechanism.

 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​​.

TheOriginator IDin a BGP route represents the Router ID of the device that originally advertised the route into the BGP domain. Since RTA originates the route10.1.1.0/24into the BGP process, the Originator ID in the route received by RTD will be set to1.1.1.1​.

 RST BPDU Handling

On an RSTP network, if a port receives an RST BPDU and determines its own buffered BPDU is superior, it discards the received BPDU without responding. This ensures stability and proper convergence in the network.

 HCIP-Datacom-Core Reference

BPDU handling is described in the RSTP operation chapters​​.

Comprehensive and Detailed In-Depth Explanation:

Internal Router (IR): A router that exists entirely within asingle OSPF area(e.g., Area 0). It doesnot have to be a Border Router (BR).

Area Border Router (ABR): A router that connectstwo or more OSPF areas. It maintains separate LSDBs for each area and forwardssummary LSAsbetween them.

Autonomous System Boundary Router (ASBR): A router that connects the OSPF domain to anexternal network(e.g., BGP, another OSPF AS).

The statement isfalsebecause:

AnIR in Area 0 does not have to be a BR(Border Router). It can just be a normal internal router.

AnASBR does not have to be an ABR. An ASBR can existinside any OSPF area, even a single area, without needing to connect multiple areas.

????Reference:Huawei HCIA-Datacom Study Guide, OSPF Router Types and Area Concepts.

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 ​.

Edge ports are used in RSTP to bypass the spanning tree calculation for ports connected to end devices. By configuring ports like SWD's GE0/0/2 and SWC's GE0/0/2 as edge ports, they transition directly to the Forwarding state upon activation, ensuring faster convergence. Statement A is incorrect because receiving BPDU invalidates the edge port status ​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Port Priority in RSTP:

RSTP (Rapid Spanning Tree Protocol) elects root and designated ports based on port priority and port ID.

Port priority is a configurable value that helps determine which port becomes the root or designated port when multiple ports are eligible.

The port ID consists of the port priority and port number. When priorities are equal, the port number is used as a tiebreaker.

2. Default Port Priority on Huawei Switches:

On Huawei switches, the default port priority is128.

This value can be adjusted in increments of 16 using the command stp port priority.

3. Analysis of Options:

Option A: 1

Incorrect. This is not the default port priority value.

Option B: 128

Correct. This is the default port priority value on Huawei switches.

Option C: 4096

Incorrect. This is not a valid default port priority value.

Option D: 32768

Incorrect. This is the default bridge priority, not the port priority.

4. Summary:

The default port priority on Huawei switches is128.

Huawei HCIA-Datacom Study Guide, Chapter "RSTP Port Role Election."

IEEE 802.1D-2004: Rapid Spanning Tree Protocol (RSTP).

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

In an Intermediate System to Intermediate System (IS-IS) network, aDesignated Intermediate System (DIS)is elected on broadcast networks to perform the following functions:

Represent the broadcast network as a pseudonode.

Generate and update the Link State Protocol Data Units (LSPs) for the pseudonode.

The DIS is elected based on theDIS priorityvalue, which is configured on IS-IS interfaces. If two routers have the same priority, the router with the higher MAC address becomes the DIS.

Thedefault DIS priorityfor IS-IS interfaces is64, which can be modified depending on the network requirements.

Option A (200):Incorrect. This is not the default value.

Option B (64):Correct. This is the default DIS priority value.

Option C (1):Incorrect. This is not the default value.

Option D (100):Incorrect. This is not the default value.

 IS-IS Overview: Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol. Routers exchangeLink State Packets (LSPs)to maintain a synchronized link-state database. These LSPs are categorized intoLevel-1 LSPs(intra-area routing) andLevel-2 LSPs(inter-area routing). Both types share the same packet format.

HCIP-Datacom-Core Technology Training Material (IS-IS LSPs and Packet Structure)​​.

 LSP ID Format: The LSP ID uniquely identifies each LSP and ensures accurate routing information. It comprises the following components:

System ID (C): A 6-byte identifier assigned to each router, derived from the router's NET (Network Entity Title). This identifier ensures unique identification of routers within the IS-IS domain.

Pseudonode ID (B): Assigned when a router acts as a Designated Intermediate System (DIS) on a broadcast network. It differentiates LSPs generated by the DIS from other routers.

LSP Number (A): A 1-byte field indicating the sequence number of the LSP. It helps distinguish multiple LSPs generated by the same router for the same level.

Comprehensive and Detailed In-Depth Explanation:

ANET (Network Entity Title)consists of three parts:

Area Address→ Identifies the IS-IS area.

System ID→ Uniquely identifies the router.

SEL (NSEL - N-selector)→ Always0in IS-IS.

TheArea Addresspart contains:

AFI (Authority and Format Identifier)→ Identifies the address type.

IDI (Initial Domain Identifier)→ Identifies the routing domain.

System ID is NOT part of the Area Address, so the correct answers areB (AFI) and C (IDI).

????Reference:Huawei HCIA-Datacom Study Guide, IS-IS Addressing and NET Structure.

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 ​.

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.

Comprehensive and Detailed In-Depth Explanation:

OSPF network typesaffect how protocol packets (Hello, LSA updates) are transmitted:

NBMA (Non-Broadcast Multi-Access)networks (e.g., Frame Relay) donot support multicast, so routers mustunicastOSPF packets to neighbors.

Broadcast networks(e.g., Ethernet) supportmulticastand use224.0.0.5 for Hello packetsand224.0.0.6 for DR/BDR communication.

The statement isfalsebecause:

NBMA does not unicast all packets—only Hello packets must bemanually configuredto be unicast.

LSAs and routing updates can still be multicastif an NBMA network is configured aspoint-to-multipoint.

????Reference:Huawei HCIA-Datacom Study Guide, OSPF Network Types and Packet Transmission.

Comprehensive and Detailed Step-by-Step Explanation:

IPv4 Address Classes:

Class D:Reserved for multicast and defined by the first four bits as1110.

Address range:224.0.0.0 to 239.255.255.255.

Structure:

Class D does not include a network/host division, as it is designed for group communication rather than device identification.

 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.

Comprehensive and Detailed Step-by-Step Explanation:

Understanding the ACL Configuration:

ACL Number:3001 is an advanced ACL.

Rule Description:The rule permits ICMP packets with the following criteria:

Source IP:192.168.1.3(host-specific).

Destination IP:192.168.2.0/24(entire subnet).

Analysis of Each Option:

Option A:True. ICMP packets from 192.168.1.3 to 192.168.2.200 (within the subnet) are permitted.

Option B:True. Packets from 192.168.1.2 (not matching the source) are denied by default.

Option C:False. The ACL only permits ICMP packets, not general IP packets.

Option D:True. The ACL is identified by the number 3001.

A is true– MAC authentication often usesPAP or CHAPfor basic password exchange.

B is false– Bydefault, both theusername and password are set to the full MAC addressof the terminal, not just the last 6 digits.

C is true– MAC authentication istransparentto the user and requiresno client softwareon the terminal.

D is true– The authentication system includes:

Terminal(user device),

Access device(AP or switch), and

Authentication server(e.g., RADIUS).

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

“MAC authentication does not require client-side software. By default, both the user name and password are the complete MAC address in lowercase without delimiters.”

(Chapter: WLAN Security – Section: MAC Authentication Mechanism)

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:

1. How Firewalls Match Security Policies:

Firewalls usesecurity policiesto define rules for filtering traffic.

Each policy containsmatching conditions(e.g., source IP, destination IP, protocol, etc.) and anaction(e.g., permit or deny).

Traffic is evaluated against these policies in sequential order, and the first matching policy is applied.

2. Analysis of Each Statement:

Option A: Multiple values can be configured for a single matching condition, and the values are logically ANDed.

Incorrect.

Multiple values for a single matching condition (e.g., multiple source IPs) are logicallyORed, not ANDed. For example, traffic from any of the specified source IPs matches the policy.

Option B: If a security policy contains multiple matching conditions, the relationship between them is AND.

Correct.

When a policy has multiple matching conditions (e.g., source IP AND destination IP AND protocol), all conditions must be met for the policy to match.

Option C: The system has a default security policy named default, where all matching conditions are any and the default action is permit.

Incorrect.

The default security policy typically denies all traffic unless explicitly permitted by user-defined policies.

Option D: When multiple security policy rules are configured, they are sorted in a list by configuration sequence by default. A security policy rule configured earlier is placed higher in the list and has a higher priority.

Correct.

Security policies are processed in sequential order based on their configuration sequence. Policies configured earlier have higher priority and are evaluated first.

3. Summary:

The correct statements areBandD.

Comprehensive and Detailed In-Depth Explanation:

A. TRUE→ Firewalls maintainsession tableswith adefault session timeout; adjusting it depends onnetwork conditions.

B. FALSE→Fast session aging does not affect persistent connection sessions. Persistent connections (e.g., TCP keepalives)maintain sessionseven if aging settings change.

C. TRUE→ Sessionsmust be constantly matchedwith ongoing traffic to remainactive.

D. TRUE→ Evenwithout stateful inspection, the firewallcreates session entriesfornon-first packetsto maintaincontinuity of services.

????Reference:Huawei HCIA-Datacom Study Guide, Firewall Session Table Mechanism.

 ACL in Routing Policies

ACLs are frequently used in routing policies to match specific routes based on criteria such as source IP, destination IP, and more. This allows ACLs to influence route redistribution, filtering, and forwarding decisions.

 HCIP-Datacom-Core Reference

ACL applications in routing policies are discussed in the routing policy chapters​​.

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

To answer this question, it is essential to distinguish between the roles of ABRs and ASBRs in OSPF and the function of route summarization:

Route Summarization on ABRs:

Route summarization in OSPF can reduce the number ofinter-area Type 3 LSAsthat ABRs propagate between areas.

ABRs perform route summarization to reduce the amount of routing information exchanged between areas, thereby decreasing the size of the routing table and improving resource utilization.

Route Summarization on ASBRs:

ASBRs summarize external routes (from outside OSPF) into Type 5 LSAs or Type 7 LSAs (in NSSAs).

ASBR route summarization does not impactinter-area Type 3 LSAsbecause ASBRs are responsible for importing and summarizingexternal routes, not summarizing routes between OSPF areas.

Since the statement refers to configuring route summarization onASBRsto reduceinter-area Type 3 LSAs, it isincorrect. Route summarization for inter-area Type 3 LSAs must be configured on ABRs, not ASBRs.

Correct Statement:Route summarization on ABRs reduces the number of inter-area Type 3 LSAs.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Origin Attribute Priority:

The Origin attribute determines the source of the route and affects the selection of the best path.

The priority order is as follows:

IGP (i):Highest priority. Routes injected using the network command.

EGP (e):Lower priority. Routes learned from the EGP protocol.

Incomplete (?):Lowest priority. Routes redistributed into BGP from other protocols.

Correct Option:

A:IGP > EGP > Incompleteis the correct order of priority.

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

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.

Network Types and Corresponding Link Layer Protocols

Broadcast: Ethernet

Point-to-Point (P2P): PPP, HDLC

Point-to-Multipoint (P2MP): PPP

Non-Broadcast Multi-Access (NBMA): Frame Relay

 OSPF Network Types:

OSPF classifies networks based on link layer protocols into the following types:

Broadcast: This type assumes that all routers on the network can communicate directly with one another using multicast or broadcast frames. Ethernet networks are typical examples.

Point-to-Point (P2P): This type is used for links that connect two routers directly. Common protocols include PPP (Point-to-Point Protocol) and HDLC.

Point-to-Multipoint (P2MP): This type simulates multiple point-to-point connections over a single physical network, often used in WAN scenarios where PPP is employed.

Non-Broadcast Multi-Access (NBMA): These networks connect multiple devices but lack native broadcast capability, such as Frame Relay.

Comprehensive and Detailed In-Depth Explanation:

STP Port Roles:

Root Port (RP)→ Connects directly to theRoot Bridge.

Designated Port (DP)→Forwards trafficfor a given segment.

RSTP introduces two additional rolesto improve redundancy:

Backup Port→ Aredundant Designated Port(on the same switch).

Alternate Port→ Abackup Root Port(path to the Root Bridge).

Allfour roles exist in RSTP, making the correct answerA, B, C, D.

????Reference:Huawei HCIA-Datacom Study Guide, RSTP Port Roles and Rapid Convergence.

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 ​.

RSTP improves convergence by introducing changes to the BPDU handling mechanism and port roles. However, RSTP does not rely on a fixed timeout of four Hello intervals for negotiation failure. Instead, RSTP uses a more dynamic mechanism to detect topology changes. The other options describe valid RSTP improvements ​.

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)

 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​​.

Application Specific Packet Filtering (ASPF) is a feature that allows the firewall to understand and handle multi-channel protocols such as FTP, H.323, and SIP. ASPF inspects the controlchannel to dynamically create temporary rules for the data channels, enabling the firewall to secure and manage complex application protocols. This feature ensures that appropriate security policies are applied to these multi-channel applications ​.

When the router ID is configured in both the system view and the BGP view, the router ID in the BGP view takes precedence because BGP-specific configurations override global settings. This ensures that BGP operates with the most relevant configurations ​.

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​.

The error indicates "Incorrect remote AS," which refers to a mismatch in the autonomous system (AS) numbers during BGP peer configuration. This issue is unrelated to the neighbor address. The neighbor address (10.1.1.5) and timestamp (2010-03-22 12:40:39) provided in the output are correct, and the error type confirms a neighbor relationship issue ​.

In the IS-IS protocol, TLV 129 (IPv4 interface address) is used to describe the IP address of an interface. Each TLV type carries specific information, and TLV 129 specifically relates to interface IP addresses ​.

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 ​.

Comprehensive and Detailed Step-by-Step Explanation:

Interface ID in IPv6:

Theinterface IDis the last 64 bits of an IPv6 address, and it uniquely identifies an interface within a subnet.

It can be generated in three ways:

Manually Configured:Explicitly assigned by an administrator.

System-Generated:The operating system assigns a random or pseudo-random value.

EUI-64 Standard:Generated based on the MAC address of the interface.

Correct Statement:

IPv6 supports all three methods for generating interface IDs.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Router ID Behavior:

The router ID uniquely identifies a BGP device in the network.

If the router ID is changed, it is equivalent to creating a new BGP instance, and the existing BGP session is reset to establish a new peer relationship.

Impact of Router ID Change:

BGP peering relies on stable identifiers. Changing the router ID disrupts the TCP session and requires reestablishing the relationship.

Comprehensive and Detailed Step-by-Step Explanation:

DHCP Configuration Issues:

Option C:The DHCP function isdisabled by defaulton Huawei devices. If the administrator forgets to enable it, clients cannot receive IP addresses.

Option D:DHCP uses broadcast messages, which do not traverse routers. If the clients and DHCP server are on different subnets, aDHCP relay agentmust be configured.

Other Options:

Option A:Multiple DHCP servers can coexist as long as their IP address pools do not overlap. This is unlikely to cause the problem.

Option B:STP does not affect DHCP operations unless it delays port activation, which is uncommon in this scenario.

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 In-Depth Explanation:

Stub areasdo not allowexternal routes(Type 5 LSAs).

SinceASBRs are responsible for redistributing external routesinto OSPF, theycannot exist in a stub area.

If an ASBR were placed in a stub area, it would attempt to inject external routes into the OSPF domain, which contradicts the stub area rules.

To allow external routes,Not-So-Stubby Areas (NSSAs)are used instead, which allowASBRsand useType 7 LSAsto carry external routes.

????Reference:Huawei HCIA-Datacom Study Guide, OSPF Area Types and ASBR Restrictions.

 OSPF Authentication Overview

OSPF supports three authentication modes:

Null Authentication: No authentication (default).

Plaintext Authentication: Uses clear-text passwords.

MD5 Authentication: Secure cryptographic authentication.

 Interface-Level Priority

When both interface-level and area-level authentication are configured, OSPF prioritizesinterface-level authentication. This ensures that interface-specific security overrides area-wide configurations for greater granularity and security.

 HCIP-Datacom-Core Reference

OSPF authentication hierarchy and configurations are detailed in the OSPF security configuration chapter​.

Comprehensive and Detailed Step-by-Step Explanation:

1. BGP Attributes Overview:

BGP uses attributes to describe the properties of routes. These attributes are classified into the following categories:

Well-Known Mandatory: Attributes that must be recognized and included in every BGP update. Examples: AS_PATH, ORIGIN, NEXT_HOP.

Well-Known Discretionary: Attributes that must be recognized but are not required in every BGP update. Examples: LOCAL_PREF, ATOMIC_AGGREGATE.

Optional Transitive: Attributes that may or may not be recognized, but must be passed along to other BGP peers. Examples: COMMUNITY.

Optional Non-Transitive: Attributes that may or may not be recognized, and are not passed along to other BGP peers. Examples: MED (Multi-Exit Discriminator).

2. Analysis of Each Option:

Option A: Atomic_Aggregate

Correct.

This is a well-known discretionary attribute. It indicates that the advertised route is an aggregate route that summarizes multiple specific routes.

Option B: Local-Preference

Correct.

This is a well-known discretionary attribute. It is used within an AS to prioritize routes, with higher values being preferred.

Option C: Community

Incorrect.

The COMMUNITY attribute is an optional transitive attribute. It is used to tag routes with specific labels to apply routing policies.

Option D: MED (Multi-Exit Discriminator)

Incorrect.

The MED attribute is an optional non-transitive attribute. It is used to influence the choice of the preferred path when there are multiple entry points into an AS.

3. Summary:

Well-Known Discretionary Attributes: Atomic_Aggregate and Local-Preference.

Huawei HCIA-Datacom Study Guide, Chapter "BGP Route Attributes."

RFC 4271: Border Gateway Protocol 4 (BGP-4).

Comprehensive and Detailed In-Depth Explanation:

A. TRUE→ EBGP-learned routescan be advertised to both IBGP and EBGP peers.

B. FALSE→BGP uses incremental updates, meaning itonly advertises changed routes, not all routes.

C. TRUE→BGP advertises only the best pathto prevent unnecessary routing information.

D. TRUE→IBGP split-horizon rule: Routeslearned from IBGP peers are not re-advertised to other IBGP peers(to prevent loops).

????Reference:Huawei HCIA-Datacom Study Guide, BGP Route Advertisement and Split-Horizon Rule.