Free CCNA | QoS | Day 47 Lab | CCNA 200-301 Complete Course

Introduction

In this tutorial, you will learn how to configure Quality of Service (QoS) on a Cisco router, as demonstrated in Jeremy's IT Lab's CCNA 200-301 course. This hands-on lab will guide you through essential concepts such as marking, class maps, policy maps, and service policies. Mastering QoS is crucial for optimizing network performance, particularly in environments with varying traffic types.

Step 1: Understand Default Markings

• Default markings are used to classify traffic as it enters the network.
• Familiarize yourself with Differentiated Services Code Point (DSCP) values, which help prioritize packets.
• Recognize that without proper markings, all traffic is treated equally, which can lead to congestion and poor performance.

Step 2: Configure Class Maps

• Class maps are used to identify and classify traffic types.
• To create a class map, use the following command in the router's configuration mode:

  class-map [class-map-name]
  

• Define the match criteria for the traffic you want to classify, such as specific protocols or access control lists (ACLs).

Step 3: Create Policy Maps

• Policy maps apply actions to the classified traffic.
• Enter policy map configuration mode with:

  policy-map [policy-map-name]
  

• Define actions like bandwidth allocation or queueing methods. For example, to set a bandwidth limit:

  bandwidth [kbps]
  

Step 4: Apply Service Policies

• Attach the policy maps to interfaces to enforce QoS.
• Use the following command in the interface configuration mode:

  service-policy [policy-map-name]
  

• This step is crucial as it dictates how the router handles the different classes of traffic.

Step 5: Check DSCP Markings

• After configuration, verify that DSCP markings are applied correctly.
• Use the command:

  show policy-map interface [interface-name]
  

• This command displays which traffic classes are being forwarded and their respective statistics.

Conclusion

You have now configured QoS on a Cisco router by understanding default markings, creating class maps, policy maps, and applying service policies. Ensuring proper QoS configuration is essential for network efficiency and performance. As a next step, consider practicing these configurations in a controlled environment, such as using Cisco Packet Tracer, to reinforce your skills and understanding.