Pass the Huawei HCIP-Datacom H12-821_V1.0 Questions and answers with CertsForce

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 In-Depth Explanation:

When a packet is checked against anAccess Control List (ACL), it is processed based on rule matches.

"Unmatched" scenariosoccur if:

A. TRUE→ The packetdoes not match any ACL rule.

C. TRUE→No ACL is configured, so there are no rules to match.

D. TRUE→An empty ACL exists, meaning no rules are defined.

B is incorrectbecauseif the packet matches a deny rule, it is "matched" and explicitly dropped, not "unmatched".

????Reference:Huawei HCIA-Datacom Study Guide, ACL Rule Matching and Processing Logic.

Comprehensive and Detailed Step-by-Step Explanation:

Multi-Channel Protocols:

Multi-channel protocols use separate channels for control and data communication, requiring application-specific packet filtering (ASPF) to track sessions.

Examples:

FTP (A):Uses separate control and data channels.

SIP (B):Uses multiple ports for signaling and media.

H.323 (D):A VoIP protocol using multiple channels.

Single-Channel Protocol:

SMTP (C):A single-channel protocol for email communication, which does not require ASPF.

Understanding the LSDB and Level-2 DIS Election in IS-IS:

In IS-IS, theDesignated Intermediate System (DIS)is elected for both Level-1 and Level-2 on broadcast networks to manage the link-state database (LSDB) and reduce the number of LSAs exchanged.

The election of the DIS is based on thehighest priority. If the priority is the same, the router with thehighest System IDbecomes the DIS.

HCIP-Datacom-Core Technology Training Material (IS-IS DIS Election)​​.

Analyzing the LSDB:

From the LSDB ofR1, the Level-2 link-state database includes the following entries:

LSPID 0100.0000.3003.00-00: This is R3, and it is present in the Level-2 LSDB with the sequence number and checksum details.

Other routers (R1, R2, R4) are present but do not have the characteristics of the Level-2 DIS in this topology.

Based on the System IDs,R3 (0100.0000.3003)has the highest System ID, making it theLevel-2 DIS.

Conclusion:

The Level-2 DIS on the network isR3, based on the election rules and the LSDB information shown in the figure.

1. Understanding Prefix List Configuration:

The command ip ip-prefix huawei index 10 permit 10.1.1.0 24 greater-equal 26 defines a prefix filter:

The base prefix is 10.1.1.0/24.

The greater-equal 26 condition specifies that the mask length of matching prefixes must beat least 26 bits.

If the less-equal parameter is not explicitly defined, the default value is32, meaning the longest possible mask length for IPv4.

2. Explanation of Values:

greater-equal-value: Specifies the minimum mask length. In this case, the value is26.

less-equal-value: Specifies the maximum mask length. Since it is not explicitly configured, the default value is32.

3. Summary:

greater-equal-value = 26

less-equal-value = 32

Huawei HCIA-Datacom Study Guide, Chapter "IP Prefix List Configuration."

The prefix list permits the prefix1.1.1.1/24with a mask length greater than or equal to/26and less than or equal to/32. This means only prefixes with the base1.1.1.1and mask lengths between/26and/32will be permitted. Routes like1.1.1.2/16and1.1.1.1/24do not meet the mask length criteria, so they will be denied. Conversely, routes like1.1.1.1/26and1.1.1.1/32satisfy the condition and will be permitted ​.

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 ​.

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 ​.

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)

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 ​.