Differences Between Per-Unit Scheduling and Shared Scheduling

Shared scheduling allows you to allocate separate pools of shared resources to subsets of logical interfaces belonging to the same physical port.

Per-unit scheduling enables one set of output queues for each logical interface configured under the physical interface.

An unconfigured logical interface (in the context of CoS) is a logical interface that you configure at the [edit interfaces interface-name unit logical-unit-number] hierarchy level, but do not configure at the [edit class-of-service interfaces interface-name unit logical-unit-number] hierarchy level.

The differences between per-unit scheduling and shared-scheduling are as follows:

• With per-unit scheduling, an unconfigured logical interface receives its own set of output queues.
• With shared scheduling, an unconfigured logical interface receives its own set of output queues only if there is some configuration for that logical interface at the [edit class-of-service interfaces interface-name unit logical-unit-number] hierarchy level.
• When you configure shared scheduling, you can include the shared-instance statement with the traffic-control profile. The shared-instance statement is not supported with per-unit scheduling.
• When you configure shared scheduling, a dedicated scheduler is assigned to a logical interface on the output direction only, if you configure one or more of the following: a scheduler map, a shaping-rate, a guaranteed rate, or a traffic-control profile. All the other logical interfaces use the same set of queues in the output direction. Similarly, a dedicated scheduler is assigned to a logical interface on the input direction only, if you configure one or more of the following: an input scheduler map, an input shaping rate, or an input traffic-control profile. All other logical interfaces use the same set of queues in the input direction.

Copyright © 2009, Juniper Networks, Inc. All rights reserved. Trademark Notice.