Huawei OSPF Route Summarization Commands and Defaults

H12-821 By islever Editorial Last updated

OSPF Route Calculation OSPF Basics

Short answer

ABC The asbr-summary command operates in the OSPF view, the abr-summary command operates in the area view, and its default behavior is to advertise the summarized route.

Question

Which of the following statements regarding OSPF route summarization commands are true? (Choose all that apply.)
  1. The asbr-summary command is executed in the OSPF view. Correct Answer
  2. The abr-summary command is executed in the OSPF area view. Correct Answer
  3. advertise is the default parameter of the abr-summary command. That is, if not-advertise is not specified in the abr-summary command, the advertise parameter takes effect by default, Correct Answer
  4. not-advertise is the default parameter of the abr-summary command. That is, if advertise is not specified in the abr-summary command, the not-advertise parameter takes effect by default.

Key Takeaways

The main trap is confusing the configuration views: asbr-summary is global (OSPF view), while abr-summary is local to an area (Area view). Additionally, understanding that 'advertise' is the default for abr-summary is critical.

Learn which statements about Huawei OSPF route summarization are true. This page explains where to configure asbr-summary and abr-summary commands and their default advertisement behavior.

Common mistake: Candidates often select D, mistakenly believing that summarization commands default to blocking traffic or require explicit permission to advertise. In reality, the default is to advertise the summary route unless 'not-advertise' is specified.

Expert Analysis

The question tests knowledge of OSPF route summarization commands on Huawei routers, specifically the scope and default behaviors of asbr-summary and abr-summary.

A. The asbr-summary command is executed in the OSPF view. This statement is correct. The asbr-summary command is used to summarize external routes (Type 5 LSAs) generated by an ASBR. Since it applies to the entire OSPF process globally, it must be configured under the OSPF process view (ospf <process-id>). As noted in the comments, this command is indeed used for summarizing external routes.

B. The abr-summary command is executed in the OSPF area view. This statement is correct. The abr-summary command is used to summarize inter-area routes (Type 3 LSAs). Because Type 3 LSAs are generated at Area Border Routers (ABRs) to filter traffic between areas, the command must be applied within a specific area context (area <area-id>).

C. advertise is the default parameter of the abr-summary command. This statement is correct. When configuring abr-summary, if you do not explicitly specify the not-advertise keyword, the router defaults to advertising the summary route into other areas. The CLI output confirms that advertise is the default action.

D. not-advertise is the default parameter of the abr-summary command. This statement is false because it contradicts Option C. The default behavior is to advertise, not suppress.

Therefore, options A, B, and C are all factually accurate regarding Huawei OSPF implementation.

Official Reference

https://support.huawei.com/enterprise/en/doc/EDOC1000194378/d4b4e6c1

This link opens the official vendor documentation in a new tab.

Exam Strategy

When facing questions about OSPF command syntax, always identify the LSA type being controlled. Type 5 (external) summaries are global process tasks, while Type 3 (inter-area) summaries are area-specific tasks. Memorize the view hierarchy: Process View > Area View > Interface View.

Frequently Asked Questions

What is the difference between asbr-summary and abr-summary?

asbr-summary summarizes external routes (Type 5 LSAs) and is configured in the OSPF process view. abr-summary summarizes inter-area routes (Type 3 LSAs) and is configured in the area view.

Does abr-summary advertise by default?

Yes. If you do not specify 'not-advertise', the router will automatically advertise the summarized route to other areas.

More H12-821 FAQ →

Discussion 4 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 4

  1. 198a491 👍 2 Answered A
    A is correct, missed that below Used for summarizing external routes (Type 5 LSA)
  2. VPGROUP 👍 1
    A, B y C son correctas. A. asbr-summary se ejecuta en la vista OSPF (process view) del router. Huawei Soporte B. abr-summary se ejecuta en la vista del área OSPF (area view). Huawei Soporte C. En abr-summary, advertise es el valor por defecto; si no se especifica not-advertise, se anuncia la ruta resumida. Huawei Soporte D. Es falsa (el valor por defecto no es not-advertise).
  3. lazizz 👍 1
    B and C - correct. Command from cli huawei router: [R1-ospf-1-area-n] abr-summary x.x.x.x y.y.y.y advertise ? advertise Advertise this summary (default) cost Set cost not-advertise Do not advertise this summary <cr> Please press ENTER to execute command
  4. 198a491 👍 1 Answered D
    D is false. The default for an ABR summary is to advertise. B is correct and is used for Type 3 (ABR) advertisement.

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