Technical Documentation

Defining CoS Schedulers (J-Web Procedure)

You can use the J-Web interface to define CoS schedulers. Using schedulers, you can assign attributes to queues and thereby provide congestion control for a particular class of traffic. These attributes include the amount of interface bandwidth, memory buffer size, transmit rate, and schedule priority.

To configure schedulers:

  1. Select Configure > Class of Service> Schedulers.
  2. Click one:
    • Add—Adds a scheduler. Enter information into the schedulers page as described in Table 1.
    • Edit—Modifies an existing scheduler. Enter information into the schedulers page as described in Table 1.
    • Delete—Deletes an existing scheduler.

Table 1: Schedulers Configuration Page

Field

Function

Your Action

Scheduler Name

Specifies the name for a scheduler.

To name a scheduler, type the name—for example, be-scheduler.

Scheduling Priority

Sets the transmission priority of the scheduler, which determines the order in which an output interface transmits traffic from the queues.

You can set scheduling priority at different levels in the order of increasing priority from low to high.

A high-priority queue with a high transmission rate might lock out lower-priority traffic.

To set a priority, select one:

  • low—Packets in this queue are transmitted last.
  • strict-high—Packets in this queue are transmitted first.
  • To specify no scheduling priority, select the blank.

Buffer Size

Defines the size of the delay buffer.

By default, queues 0 through 7 are allotted the following percentage of the total available buffer space:

  • Queue 0—95 percent
  • Queue 1—0 percent
  • Queue 2—0 percent
  • Queue 3—0 percent
  • Queue 4—0 percent
  • Queue 5—0 percent
  • Queue 6—0 percent
  • Queue 7—5 percent

Note: A large buffer size value correlates with a greater possibility of packet delays. Such a value might not be practical for sensitive traffic such as voice or video.

To define a delay buffer size for a scheduler, select the appropriate option:

  • To specify no buffer size, select the blank.
  • To specify buffer size as a percentage of the total buffer, select Percent and type an integer from 1 through 100.
  • To specify buffer size as the remaining available buffer, select Remainder.

Note: On EX8200 switches, you can specify the buffer size as a temporal value. The queuing algorithm will then drop packets once it has queued a computed number of bytes. This number is the product of the logical interface speed and the configured temporal value.

Shaping Rate

Specifies the rate at which queues transmit packets.

  • To specify shaping rate as a percentage, select Percent and type an integer from 1 through 100.
  • To specify shaping rate as a number, select Rate and enter a value.
  • To specify no shaping rate, select the blank.

Transmit Rate

Defines the transmission rate of a scheduler.

The transmit rate determines the traffic bandwidth from each forwarding class you configure.

By default, queues 0 through 7 are allotted the following percentage of the transmission capacity:

  • Queue 0—95 percent
  • Queue 1—0 percent
  • Queue 2—0 percent
  • Queue 3—5 percent
  • Queue 4—0 percent
  • Queue 6—0 percent
  • Queue 7—5 percent

To define a transmit rate, select the appropriate option:

  • To enforce the exact transmission rate, select Rate and enter a value.
  • To specify the remaining transmission capacity, select Remainder Available.
  • To specify a percentage of transmission capacity, select Percent and type an integer from 1 through 100.
  • To specify no transmit rate, select the blank.

Published: 2010-02-21