What are the best practices for configuring QoS?

1 Understand your network requirements

Before you start configuring QoS, you need to have a clear understanding of your network requirements and goals. You should identify the types of traffic that are critical, sensitive, or best-effort for your network, and how much bandwidth they need. You should also monitor your network baseline and performance metrics, such as utilization, throughput, delay, jitter, and error rate. This will help you determine the current and expected QoS levels, and identify any bottlenecks or issues that need to be addressed.

2 Choose the right QoS model

When selecting a QoS model for your network, you should consider the size, complexity, and design of your network. Integrated Services (IntServ) is a model that uses a signaling protocol, such as Resource Reservation Protocol (RSVP), to reserve bandwidth and resources for each traffic flow. This provides strict QoS guarantees, but is not suitable for large networks. Differentiated Services (DiffServ) is another model that uses a marking scheme, such as Differentiated Services Code Point (DSCP), to assign priority levels to each packet. This offers flexible and scalable QoS, but does not guarantee resource allocation. Lastly, the Best Effort model does not use any QoS mechanism and treats all traffic equally. This is simple to implement, but does not provide any QoS assurance. Ultimately, you should choose the QoS model that best suits your network requirements and capabilities, and apply it consistently across your network devices and segments.

3 Implement QoS policies and tools

Once you've chosen your QoS model, you need to implement QoS policies and tools to enforce your traffic classification and management. QoS policies are sets of rules that specify how to treat different types of traffic, such as priority, bandwidth, delay, and more. To do this, you can use various tools such as marking, shaping, policing, queuing, scheduling, and congestion management. Marking assigns a QoS label or value to each packet based on its source, destination, protocol, or application. Shaping adjusts the rate of traffic to match a predefined limit or profile. Policing limits the rate of traffic to a predefined threshold or limit. Queuing stores and forwards traffic packets in different queues based on their priority or class. Scheduling determines the order and timing of sending traffic packets from different queues. And congestion management detects and mitigates network congestion through algorithms or protocols that adjust the traffic rate or window size. It's essential to choose the right QoS policies and tools for your network devices, interfaces, and links so they match your QoS model and objectives.

4 Test and monitor QoS

After you implement QoS, it's essential to test and monitor its effectiveness and impact on your network. To do this, you should use tools and methods that measure and verify the QoS levels and metrics. For example, simulation uses software or hardware tools to generate and send traffic to your network, analyze the QoS results, and identify any potential problems or errors. Monitoring also uses software or hardware tools to collect data about your network traffic and QoS parameters, helping you evaluate and optimize performance. It's important to test and monitor QoS regularly and proactively, making adjustments or improvements as needed.

5 Document and review QoS

After you test and monitor QoS, it is essential to document and review its results and outcomes. You should create and maintain a QoS documentation that covers your network requirements and goals, your QoS model and policies, your QoS configuration and tools, your QoS testing and monitoring methods and data, your QoS analysis and evaluation, as well as your QoS recommendations and actions. It is important to review this documentation periodically and systematically, updating it if necessary as your network changes or evolves. Doing so will help you stay on top of the status and progress of your QoS, while also ensuring its alignment with your network needs and expectations.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?