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QoS Design Principles and Best Practices

Chapter Description

In this sample chapter from Designing for Cisco Network Service Architectures (ARCH) Foundation Learning Guide: CCDP ARCH 300-320, 4th Edition, the authors cover some best practice QoS design principles and QoS strategy models that are used to implement the numerous QoS tools we have at our disposal. Remember that usually, more than one solution fits the given QoS requirements, so simplifying the models leveraged can significantly accelerate and ensure proper QoS deployment.

Review Questions

After answering the following questions, please refer to Appendix A, “Answers to Review Questions,” for the answers.

  1. Which of the following is recommended for a QoS queuing design?

    1. You should implement queuing policy very selectively.

    2. Classes should share queues in order to save resources.

    3. You should use at minimum 4 classes of queuing behavior.

    4. You should use at minimum 11 classes of queuing behavior.

  2. Match the application classes with their PHBs as per RFC 4594.

  3. VoIP Telephony

    EF

    Transactional Data

    CS1

    Network Control

    CS6

    Call Signaling

    CS4

    Real-time Interactive

    AF21

  4. Select the four classes of the 4-class QoS model.

    1. Voice, signaling, mission-critical data, and best effort

    2. Video, signaling, mission-critical data, and best effort

    3. Voice, signaling, mission-critical data, and scavenger

    4. Real-time interactive, signaling, mission-critical data, and best effort

  5. Why is it recommended to leverage DSCP markings wherever possible?

    1. Support for end-to-end Layer 3 marking.

    2. It is a more granular method of marking that supports 64 levels as compared to CoS and MPLS EXP, which have 8 levels.

    3. It is more extensible than Layer 2 markings because these markings are lost when media change.

    4. All the above.

    5. None of the above.

  6. Traffic should be marked down using which RFC recommendations? (Select two.)

    1. RFC 2957

    2. RFC 2597

    3. RFC 2698

    4. RFC 2968

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