Home > Articles > Certification > Cisco Certification > CCNP

CCNP Exam Prep: Traditional Spanning Tree Protocol

This chapter discusses the theory and operation of the STP with an eye toward passing the CCNP BCMSN Exam. More specifically, the original, or traditional, STP is covered, as defined in IEEE 802.1D.
This chapter is from the book

This chapter is from the book

CCNP BCMSN Exam Certification Guide, 3rd EditionCCNP BCMSN Exam Certification Guide, 3rd Edition

Learn More Buy

This chapter is from the book

This chapter is from the book

CCNP BCMSN Exam Certification Guide, 3rd EditionCCNP BCMSN Exam Certification Guide, 3rd Edition

Learn More Buy

This chapter covers the following topics that you need to master for the CCNP BCMSN exam:

  • IEEE 802.1D Overview— This section discusses the original, or more traditional, Spanning Tree Protocol (STP). This protocol is the foundation for the default Catalyst STP and for all the enhancements that are described in Chapters 10, "Spanning Tree Configuration," through 12, "Advanced Spanning Tree Protocol."
  • Types of STP— This section discusses other types of STP that might be running on a Catalyst switch—specifically, the Common Spanning Tree, Per-VLAN Spanning Tree (PVST), and PVST+.

Previous chapters covered robust network designs where redundant links are used between switches. Although this increases the network availability, it also opens up the possibility for conditions that would impair the network. In a Layer 2 switched network, preventing bridging loops from forming over redundant paths is important. Spanning Tree Protocol (STP) was designed to monitor and control the Layer 2 network so that a loop-free topology is maintained.

This chapter discusses the theory and operation of the STP. More specifically, the original, or traditional, STP is covered, as defined in IEEE 802.1D. Several chapters explain STP topics in this book. Here is a brief roadmap so you can chart a course:

  • Chapter 9, "Traditional Spanning Tree Protocol"— Covers the theory of IEEE 802.1D
  • Chapter 10, "Spanning Tree Configuration"— Covers the configuration commands needed for IEEE 802.1D
  • Chapter 11, "Protecting the Spanning Tree Protocol Topology"— Covers the features and commands to filter and protect a converged STP topology from conditions that could destabilize it
  • Chapter 12, "Advanced Spanning Tree Protocol"— Covers the newer 802.1w and 802.1s enhancements to STP, allowing more scalability and faster convergence

"Do I Know This Already?" Quiz

The purpose of the "Do I Know This Already?" quiz is to help you decide whether you need to read the entire chapter. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now.

The 12-question quiz, derived from the major sections in the "Foundation Topics" portion of the chapter, helps you determine how to spend your limited study time.

Table 9-1 outlines the major topics discussed in this chapter and the "Do I Know This Already?" quiz questions that correspond to those topics.

Table 9-1. "Do I Know This Already?" Foundation Topics Section-to-Question Mapping

Foundation Topics Section

Questions Covered in This Section

Score

IEEE 802.1D

1–10

  

Types of STP

11–12

  

Total Score

    

Caution

The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark this question wrong. Giving yourself credit for an answer you correctly guess skews your self-assessment results and might give you a false sense of security.

  1. How is a bridging loop best described?

    1. A loop formed between switches for redundancy
    2. A loop formed by the Spanning Tree Protocol
    3. A loop formed between switches where frames circulate endlessly
    4. The round-trip path a frame takes from source to destination

  2. Which of these is one of the parameters used to elect a Root Bridge?

    1. Root Path Cost
    2. Path Cost
    3. Bridge Priority
    4. BPDU revision number

  3. If all switches in a network are left at their default STP values, which one of the following is not true?

    1. The Root Bridge will be the switch with the lowest MAC address.
    2. The Root Bridge will be the switch with the highest MAC address.
    3. One or more switches will have a Bridge Priority of 32,768.
    4. A secondary Root Bridge will be present on the network.

  4. Configuration BPDUs are originated by which of the following?

    1. All switches in the STP domain
    2. Only the Root Bridge switch
    3. Only the switch that detects a topology change
    4. Only the secondary Root Bridge when it takes over

  5. Which of these is the single most important design decision to be made in a network running STP?

    1. Removing any redundant links
    2. Making sure all switches run the same version of IEEE 802.1D
    3. Root Bridge placement
    4. Making sure all switches have redundant links

  6. What happens to a port that is neither a Root Port nor a Designated Port?

    1. It is available for normal use.
    2. It can be used for load balancing.
    3. It is put into the Blocking state.
    4. It is disabled.

  7. What is the maximum number of Root Ports that a Catalyst switch can have?

    1. 1
    2. 2
    3. Unlimited
    4. None

  8. What mechanism is used to set STP timer values for all switches in a network?

    1. Configuring the timers on every switch in the network.
    2. Configuring the timers on the Root Bridge switch.
    3. Configuring the timers on both primary and secondary Root Bridge switches.
    4. The timers can't be adjusted.

  9. MAC addresses can be placed into the CAM table, but no data can be sent or received if a switch port is in which of the following STP states?

    1. Blocking
    2. Forwarding
    3. Listening
    4. Learning

  10. What is the default "hello" time for IEEE 802.1D?

    1. 1 second
    2. 2 seconds
    3. 30 seconds
    4. 60 seconds

  11. Which of the following is the Spanning Tree Protocol defined in the IEEE 802.1Q standard?

    1. PVST
    2. CST
    3. EST
    4. MST

  12. If a switch has 10 VLANs defined and active, how many instances of STP will run using PVST+ versus CST?

    1. 1 for PVST+, 1 for CST
    2. 1 for PVST+, 10 for CST
    3. 10 for PVST+, 1 for CST
    4. 10 for PVST+, 10 for CST

You can find the answers to the quiz in Appendix A, "Answers to Chapter 'Do I Know This Already?' Quizzes and Q&A Sections." The suggested choices for your next step are as follows:

  • 7 or less overall score— Read the entire chapter. This includes the "Foundation Topics," "Foundation Summary," and "Q&A" sections.
  • 8–10 overall score— Begin with the "Foundation Summary" section and then follow up with the "Q&A" section at the end of the chapter.
  • 11 or more overall score— If you want more review on these topics, skip to the "Foundation Summary" section and then go to the "Q&A" section at the end of the chapter. Otherwise, move to Chapter 10.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020