Which configuration part specifies the traffic class for LLQ?

350-801 By islever Editorial Last updated

Short answer

B policy map

Question

An engineer is configuring LLQ in a network and completes the section for identifying different DSCP markings. Which part of the configuration specifies the traffic class for LLQ?
  1. class map
  2. policy map Correct Answer
  3. service policy
  4. access list

Key Takeaways

The exam tests the distinction between defining traffic (class-map) and applying actions like LLQ (policy-map). The common trap is confusing the classification step with the enforcement step.

This question tests the understanding of Cisco IOS Quality of Service (QoS) hierarchy, specifically how Low Latency Queuing (LLQ) is implemented. The community consensus and official documentation confirm that the policy map is where the LLQ priority command is applied to a defined class.

Common mistake: Option A (class map) is chosen by some candidates who correctly identify that class maps define traffic but mistakenly believe they also specify the LLQ action. However, class maps only match traffic; they do not configure queuing behavior.

Expert Analysis

Why the Answer Is Correct

In Cisco IOS QoS configuration, the Policy Map is the component where specific actions are assigned to traffic classes. To implement Low Latency Queuing (LLQ), you must use the priority command within the policy map configuration mode. This command explicitly defines the traffic as belonging to the LLQ class, ensuring it receives strict priority queuing.

Why the Other Options Are Wrong

A Class Map (Option A) is used solely to classify and match traffic based on criteria like DSCP or ACLs; it does not contain QoS actions like queuing. An Access List (Option D) is often used within a class map to match traffic but is not the structure that applies LLQ. A Service Policy (Option C) refers to the application of the policy map to an interface (service-policy output/policy-name), not the internal configuration of the LLQ parameters themselves.

Community Comment Notes

Comment [1] provides the official Cisco documentation steps, confirming that the policy-map section includes the priority command required for LLQ. Comment [2] clearly outlines the three-step sequence: Class Map (define/match), Policy Map (apply behavior/LLQ), and Service Policy (apply to interface). Comment [3] argues for Option A, likely confusing the identification of the class with the specification of the LLQ mechanism, which is technically incorrect in the context of 'configuring LLQ'.

Exam Strategy

Memorize the QoS workflow order: Match (Class Map) -> Action (Policy Map) -> Apply (Service Policy). When asked about 'configuring LLQ' or 'assigning priority', always look for the Policy Map, as this is where the priority keyword resides.

Community Votes

B
80%
A
20%

80% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 5 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 5

  1. TheBabu 👍 4 Answered B
    I believe it should be B, policy-map, per this document: SUMMARY STEPS enable configure terminal policy-map policy-map class {class-name | class-default } priority {bandwidth-kbps | percent percentage } [burst ] bandwidth {bandwidth-kbps | percent percentage | remaining percent percentage } end https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_conmgt/configuration/xe-16-12/qos-conmgt-xe-16-12-book/qos-conmgt-llq-pps.html
  2. b3532e4 👍 1
    Based on the detailed configuration process, the part of the configuration that specifies the traffic class for LLQ is: A. class map The class map defines and identifies traffic classes, which are then referenced in the policy map where specific Quality of Service (QoS) actions, such as Low Latency Queueing (LLQ), are applied
  3. ChrisLinda 👍 1
    The steps generally follow this sequence: Class map: Define and match the traffic. Policy map: Apply queuing and priority behavior, such as LLQ. Service policy: Apply the policy map to an interface.
  4. pasangawa 👍 1 Answered A
    class {class-name | class-default} Specifies the class so that you can configure or modify its policy. Enters policy-map class configuration mode.
  5. Ste1233 👍 1
    i think its A as you need policy map as top end then class map configure or modify policy to select class

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