Traffic-Class Groups

You can put traffic classes into a group to create a hierarchy of scheduler nodes and queues. Organizing traffic into multiple traffic-class groups enables you to manage and shape traffic—by service class, for example—when the traffic classes are distributed across different VCs. A traffic-class group contains one or more traffic classes, but a particular traffic class can belong to a single group—either the default group or one named group.

Previous releases of the JUNOSe software supported a single strict-priority traffic-class group. Now you can configure an auto-strict group and up the three extended traffic-class groups. You must put traffic classes that require strict priority scheduling in the auto-strict group. You can optionally put traffic classes that need a separate round robin (for example, video) in an extended group.

A traffic class that is not contained in any named group is considered to belong to the default group. Traffic classes are placed in the default traffic-class group when the classes are configured—you can then move a class to another traffic-class group. When you delete a traffic-class from a named group, the class is automatically moved to the default traffic-class group. ATM VC nodes that are configured in the default group (which is the factory default configuration) receive backpressure from the segmentation and reassembly (SAR) feature.

Traffic-class groups are global in scope by default. However, you may wish to manage certain traffic classes through particular line modules. If you have already created a traffic-class group, you can subsequently specify a slot number to create a local instance of the group that is restricted to the module occupying that slot. Characteristics configured for the local group on the line module override those of the global group, for only that line module. Traffic classes in a globally scoped traffic-class group cannot belong to any other group. Traffic classes in a local traffic-class group cannot belong to any other group.

Configuring Traffic-Class Groups

To configure a traffic-class group:

1. Create a traffic-class group and enter Traffic Class Group Configuration mode.

host1(config)#traffic-class-group assuredForwarding 

host1(config-traffic-class-group)#

2. Add traffic classes to the traffic-class group.

host1(config-traffic-class-group)#traffic-class low-latency-traffic-class

traffic-class

• Use to add a traffic class to the traffic-class group.
• Example

host1(config-traffic-class-group)#traffic-class low-latency-traffic-class

• Use the no version to delete a traffic class from a traffic-class group.

traffic-class-group

• Use to configure a traffic-class group and enter Traffic Class Group Configuration mode, from which you can add classes to or delete classes from the group.
• If you do not specify a keyword, the group is strict-priority by default.
• You can use the auto-strict-priority keyword to explicitly configure a single traffic-class group with strict-priority scheduling, regardless of the scheduler profile associated with the group node.
• You can use the extended keyword to configure up to three extended traffic-class groups. Scheduling for these groups is determined by the scheduler profile associated with the group node. If an explicitly configured strict-priority group exists, the scheduler for the extended groups may not specify strict-priority scheduling.
• Use the slot slotNumber option to associate a pre-existing global traffic-class group with the module occupying that slot. Characteristics configured for the local group on the line module override those of the global group.
• Example

host1(config)#traffic-class-group assured slot 9 extended

host1(config-traffic-class-group)#

• Use the no version to remove the selected traffic-class group. You must remove all local (slot-based) instances of a traffic-class group before you can remove the global group.