Motorola AT&T NVG589, Administrator'S Hanbook

Page: 208 / 216

Administrator’s Handbook
208
Figure 3. Illustration of priority scheduling
Figure 4. Illustration of weighted fair queue scheduling
Figure 5. Illustration of a hybrid queue that is both priority and WFQ, to both constrain bandwidth usage and expedite
one of the queues.
After the packet has been classified, it can be put in the proper queue. Queues are assigned to inter-
faces and can be constructed of several queue components to deliver the desired behavior. The com-
ponents of an interface queue are these building blocks:
■ basic queues: a 1 input 1 output packet list with a length of 64 packets by default. Packets will tail-
drop when the enqueued to a full basic queue.
■ priority queue: 2 or more input, 1 output. Schedules the packets from the various inputs strictly
according to input's priority.
■ weighted fair queue: 1 or more input, 1 output. Schedules the packets according to bandwidth con-
straints
Packets are enqueued to basic queues, and only to basic queues. Basic queues are output to priority
queues and weighted fair queues, which act as “plumbing” elements that alter the dequeuing order
and rate, respectively. Priority queues and weighted fair queues can contain one another.