Interfaces are parts of the system to which we can apply Vyatta NOS QoS policies.

While you can define as many QoS policies as you like, they won't do anything until you attach/apply/associate a QoS policy to some sort of interface. QoS policies work on a stream of traffic. There can be a stream of traffic flowing freely through an interface. By applying a QoS policy to that interface you can affect how that stream of traffic flows.

There are different types of interface:

• Dataplane
• VIF/vLAN
• Switch port
• Bridge
• vHost
• Link aggregation group (LAG) — also known as 'bonded interfaces' in the CLI

On software platforms, QoS policies describe the whole classification and queuing configuration.

On hardware platforms, QoS policies describe part of the classification and all of the queuing configuration.

You can attach a single QoS policy to each interface, if you need to.

You can also attach a single QoS policy to multiple interfaces. In this case, each instance of this one QoS policy will operate independently.