H12-821_V1.0 Exam Dumps - Huawei HCIP-Datacom Questions and Answers

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.

 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​​.

 Additional Port Roles in MSTP

Master Port : Indicates the port on the shortest path to the root bridge in a region.

Regional Edge Port : Identifies a port at the boundary of the MST region.

Backup and edge ports exist in RSTP and are not newly introduced by MSTP.

 HCIP-Datacom-Core Reference

MSTP port roles are elaborated in the MSTP configuration sections​​.

Comprehensive and Detailed Step-by-Step Explanation:

1. Understanding the Prefix List Configuration:

The command ip ip-prefix test index 10 permit 10.0.0.0 8 less-equal 32 defines the following:

The prefix base is 10.0.0.0 with a mask length of 8 bits.

The less-equal 32 condition allows routes with mask lengths ranging from 8 to 32 bits to match.

2. Analysis of Each Route:

Option A: 10.1.1.1/32

Correct .

The prefix 10.1.1.1/32 falls within the 10.0.0.0/8 network range and has a mask length of 32 bits, which satisfies the less-equal 32 condition.

Option B: 10.1.1.0/6

Incorrect .

The prefix 10.1.1.0/6 has a mask length of 6 bits, which is shorter than the base prefix length of 8. It does not satisfy the condition.

Option C: 10.1.1.0/24

Correct .

The prefix 10.1.1.0/24 falls within the 10.0.0.0/8 network range and has a mask length of 24 bits, which satisfies the less-equal 32 condition.

Option D: 10.0.0.0/16

Correct .

The prefix 10.0.0.0/16 falls within the 10.0.0.0/8 network range and has a mask length of 16 bits, which satisfies the less-equal 32 condition.

3. Summary:

The prefixes that match the configuration are 10.1.1.1/32, 10.1.1.0/24, and 10.0.0.0/16.

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. Understanding the AS-Path Filter:

The as-path-filter command is used in BGP to filter routes based on the AS_PATH attribute.

In this configuration:

The filter si is defined with the regular expression _65500$.

The _65500$ expression specifies that the AS_PATH must end with 65500, meaning that the route ' s last hop must have passed through AS 65500.

2. Option Analysis:

Option A: It accepts only the routes whose AS_Path contains AS 65500.

Incorrect .

The _65500$ filter specifically matches routes where AS 65500 is the last AS in the AS_PATH. A route may contain AS 65500 somewhere in the middle of the AS_PATH but will not match this filter unless it is the last AS.

Option B: It accepts only the routes originated from AS 65500.

Incorrect .

Routes that originate from AS 65500 have an AS_PATH that starts with 65500. However, the filter _65500$ only matches routes where AS 65500 is the last AS, not the first AS.

Option C: It accepts only the routes that last pass through AS 65500.

Correct .

The _65500$ filter ensures that the AS_PATH ends with 65500. This means that the route must have last passed through AS 65500 before being received by the local BGP router.

Option D: It accepts only the routes forwarded by AS 65500.

Incorrect .

While AS 65500 may forward the route, this is not what the filter _65500$ specifically checks for. It only ensures that AS 65500 is the last AS in the AS_PATH.

3. Summary:

The as-path-filter with _65500$ accepts only the routes where AS 65500 is the last AS in the AS_PATH.

Comprehensive and Detailed In-Depth Explanation:

Type 1 LSAs (Router LSAs) are generated by every OSPF router to describe its directly connected links and their states.

The Router ID (RID) must be unique in an OSPF domain; otherwise, OSPF calculations will fail due to ambiguous paths .

If two routers in the same area have the same Router ID , OSPF will fail to calculate Shortest Path First (SPF) correctly, leading to routing inconsistencies.

To prevent this, Huawei routers automatically detect duplicate Router IDs and prevent OSPF from functioning properly until the issue is resolved.

???? Reference: Huawei HCIA-Datacom Study Guide, Chapter on OSPF LSAs and Router ID Uniqueness.

Explanation of Root Port Election in STP:

In a Spanning Tree Protocol (STP) network, the Root Port is selected on each switch (except the Root Bridge). The Root Port is the port with the lowest path cost to the Root Bridge. If there is a tie in path cost, the following criteria are used in sequence to break the tie:

Steps for Root Port Election in Sequence:

RPC Comparison (Root Path Cost):

The port with the lowest Root Path Cost is preferred.

Root Path Cost is the cumulative cost of the path to the Root Bridge.

Peer BID (Bridge ID) Comparison:

If the Root Path Costs are equal, the Bridge ID of the connected switch (peer) is compared.

The port connecting to the switch with the lower Bridge ID is preferred.

Peer PID (Port ID) Comparison:

If the Bridge IDs are equal, the Port ID of the peer ' s sending port is compared.

The port connecting to the lower Port ID is preferred.

Local PID (Port ID) Comparison:

If all else is equal, the Local Port ID of the switch is used.

The port with the lower Local Port ID is selected.

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 ​.