A QoS class determines the priority and bandwidth for traffic matching a QoS Policy rule. You can use a QoS Profile rule to define QoS classes. There are up to eight definable QoS classes in a single QoS profile. Unless otherwise configured, traffic that does not match a QoS class is assigned a class of 4.

QoS Priority Queuing and QoS Bandwidth Management, the fundamental mechanisms of a QoS configuration, are configured within the QoS class definition (see Step Add a QoS profile rule.). For each QoS class, you can set a priority (real-time, high, medium, and low) and the maximum and guaranteed bandwidth for matching traffic. QoS priority queuing and bandwidth management determine the order of traffic and how traffic is handled upon entering or leaving a network.