Key Components
Interface Egress Queues – When a physical interface tries to send more traffic than its bandwidth permits, packets are queued in one of a few different numbered queues
Interface Bandwidth Definition – You should manually define the bandwidth of an interface if it is lower than the line speed. For example, a 1gbit interface connected to a 200mbit fibre ethernet line needs to be defined as being 200mbit else it will assume 1gbit and QoS will not work
Forwarding Classes – These effectively assign a name to a numbered queue, for example assured-forwarding
Assignment of traffic to a forwarding class – This can be done in a number of ways:
Classifiers – These observe DSCP, Inet Precedence or other marker types to assign ingress traffic to forwarding classes
Firewall Rules – Ingress traffic can be matched with firewall rules and assigned to forwarding classes
Drop Profiles – A drop profile defines the probability of packets being dropped when a queue reaches a certain size
Schedulers – These define how differently queued egress traffic is prioritized
Scheduler Maps – These link forwarding classes to schedulers