QoS hardware queues scheduling

QoS queuing can be done in hardware or software queues. Their capability and which one you use depends on the platform you use.

For example, on Cisco IOS routers there is a hardware queue but you can only configure the queue length. If you want more advanced queuing, you configure it with software queues.

Cisco switches have more advanced hardware queues to perform queuing, scheduling, and packet memory management. Their capability is platform-specific.

Lower-end devices will have a single hardware queue per port. More advanced devices will have multiple hardware queues such as:

• 2Q3T
• 8Q3T
• 1P1Q3T
• 2P6Q3T

These are different models of queuing. For example, 2P6Q3T means there are two priority queues, six queues, and three drop thresholds.

Also, these queues are different for inbound and outbound traffic.

An alternative to hardware queues are Software Queues.