How do you prioritize different types of traffic using QoS policies?

2 How to classify traffic?

The first step in implementing QoS is to identify and categorize the different types of traffic on your network. You can use various criteria to classify traffic, such as source and destination addresses, port numbers, protocol types, or application signatures. You can also use predefined or custom classes of service (CoS) or differentiated services code points (DSCP) to label traffic with different levels of priority and treatment. For example, you can use CoS values from 0 to 7 or DSCP values from 0 to 63 to mark traffic with different levels of importance.

3 How to queue traffic?

After you classify traffic, you need to decide how to handle it on the network devices. Using queuing methods, packets can be sorted and stored in buffers before being sent to the next hop. These methods can be either static or dynamic and can affect the order, delay, and drop rate of packets. Common queuing methods include First-in first-out (FIFO), Priority queuing (PQ), Weighted fair queuing (WFQ), Class-based weighted fair queuing (CBWFQ), and Low latency queuing (LLQ). FIFO is the simplest method, sending packets in the order they arrive without any priority or differentiation. PQ assigns packets to different queues based on their priority, while WFQ takes into account the weight of each packet. CBWFQ allows custom classes and weights for different traffic types, and LLQ combines PQ and CBWFQ by creating a strict priority queue for delay-sensitive traffic.

4 How to shape traffic?

Sometimes, you may need to control the rate at which traffic is sent or received on a network interface. To do this, you can use traffic shaping techniques to adjust the traffic flow and match it to the available bandwidth or the downstream capacity. This can help prevent or reduce congestion, packet loss, and jitter, and also ensure compliance with service level agreements (SLAs). Common techniques include policing, which monitors the traffic rate and either drops or marks packets that exceed a predefined threshold or limit; shaping, which buffers and delays packets that exceed a predefined rate or limit; leaky bucket, which uses a fixed-size buffer and a constant output rate to smooth out traffic bursts and spikes; and token bucket, which uses a variable-size buffer and a token mechanism to allow some degree of burstiness and flexibility in traffic flow.

5 How to manage traffic?

Finally, to ensure the effectiveness of your QoS policies, you must monitor and evaluate them regularly. To do this, you can use SNMP, NetFlow, IP SLA, and QoS reports to collect and analyze network statistics and trends. With QoS policies, you can prioritize different types of traffic on your network and optimize its performance. This will help you reach your business objectives and provide a better user experience.

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?