Huawei H12-821_V1.0 - HCIP-Datacom-Core Technology V1.0

Comprehensive and Detailed In-Depth Explanation:

STP Port Roles :

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

Designated Port (DP) → Forwards traffic for a given segment.

RSTP introduces two additional roles to improve redundancy:

Backup Port → A redundant Designated Port (on the same switch).

Alternate Port → A backup Root Port (path to the Root Bridge).

All four roles exist in RSTP , making the correct answer A, B, C, D .

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

Comprehensive and Detailed Step-by-Step Explanation:

Route Policy Overview:

A route-policy is a policy-based routing tool that filters and modifies routing information.

It consists of one or more nodes , 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 is 1024 , allowing flexibility in route filtering and control.

Comprehensive and Detailed Step-by-Step Explanation:

BGP Router ID Selection Rules:

If a router ID is not manually configured:

The largest loopback address is selected as the router ID.

If no loopback interfaces exist, the largest active physical interface address is selected.

Default Behavior:

This ensures that a stable and unique router ID is chosen automatically, even without manual configuration.

A Totally Stubby Area in OSPF is a special type of stub area where only intra-area (Type 1) LSAs , router LSAs , and default routes (Type 3 LSA with 0.0.0.0/0) are allowed to be injected. It blocks inter-area routes (Type 3 LSAs for specific prefixes) and Type 5 LSAs (external routes) to reduce the size of the Link-State Database (LSDB) and enhance router performance.

Explanation of the Options:

A. Type 3 specific LSA – ❌ Correct Answer . These LSAs represent inter-area routes. Totally Stubby Areas do not allow Type 3 LSAs for specific routes , only for the default route (0.0.0.0/0).

B. Type 1 LSA – ✅ Allowed. These are Router LSAs generated by routers within the area and are necessary for OSPF to function.

C. Type 3 LSA that describes a default route – ✅ Allowed. This is the only Type 3 LSA permitted in a Totally Stubby Area. It provides a default route (0.0.0.0/0) to reach external destinations.

D. Type 2 LSA – ✅ Allowed if there are broadcast or NBMA networks in the area. These describe the network segment in multi-access environments and are generated by the DR.

Official Huawei Reference:

📘 Huawei HCIP-Datacom-Core Technology Study Guide –

Chapter: OSPF Special Areas

" A totally stub area does not allow inter-area Type 3 LSAs or external Type 5 LSAs to enter. Only a default route is injected in the form of a Type 3 LSA (0.0.0.0/0), which greatly reduces the LSDB size. "

📚 Also refer to:

Huawei VRP Command Guide > OSPF > Configuration Notes > OSPF Special Areas

ï‚· BGP Keepalive Message Behavior

Keepalive messages are used to maintain the Established state of a BGP peer relationship.

The Keepalive timer determines the frequency of these messages and defaults to 60 seconds , as per the BGP specification.

ï‚· HCIP-Datacom-Core Reference

The Keepalive timer default value is covered in the BGP configuration and operational principles​​.

ï‚· Neighbor Discovery Protocol (NDP) :

NDP is a key protocol in the IPv6 protocol suite, replacing ARP (Address Resolution Protocol) in IPv4.

It operates using ICMPv6 (Internet Control Message Protocol for IPv6) and is critical for managing interactions between IPv6 nodes on the same link.

ï‚· 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.

ï‚· HCIP-Datacom-Core Reference

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

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 ​.