It is helpful to think of forwarding classes as output queues. In effect, the end result of classification is the identification of an output queue for a particular packet. For a classifier to assign an output queue to each packet, it must associate the packet with one of the following forwarding classes:
For M-series routers (except the M320 router), you can configure up to four forwarding classes, one of each type: expedited forwarding (EF), assured forwarding (AF), best effort (BE), and network control (NC).
The M320 and T-series routing platforms support 16 forwarding classes, enabling you to classify packets more granularly. For example, you can configure multiple classes of EF traffic: EF, EF1, and EF2. The software supports up to eight output queues; therefore, if you configure more than eight forwarding classes, you must map multiple forwarding classes to single output queues. For more information, see Configuring Up to 16 Forwarding Classes.
By default, the loss priority is low. On most platforms, you can configure high or low loss priority. On the following platforms you can configure high, low, medium-high, or medium-low loss priority:
For more information, see the J-series documentation and Configuring Tricolor Marking Policers.
To configure CoS forwarding classes, include the forwarding-classes statement at the [edit class-of-service] hierarchy level:
- [edit class-of-service]
- forwarding-classes {
- class class-name queue-num queue-number priority (high | low);
- queue queue-number class-name priority (high | low);
- }
- interfaces {
-
- interface-name {
-
- unit logical-unit-number {
- forwarding-class class-name;
- }
- }
- }
- restricted-queues {
- forwarding-class class-name queue queue-number;
- }
This chapter discusses the following topics:
