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Example: Configuring Traffic Control Profiles (Priority Group Scheduling)

A traffic control profile defines the output bandwidth and scheduling characteristics of forwarding class sets (priority groups). The forwarding classes (queues) mapped to a forwarding class set share the bandwidth resources that you configure in the traffic control profile. A scheduler map associates forwarding classes with schedulers to define how the individual queues in a forwarding class set share the bandwidth allocated to that forwarding class set.

Requirements

This example uses the following hardware and software components:

  • A Juniper Networks QFX3500 Switch
  • Junos OS Release 11.1 or later for the QFX Series

Overview

The parameters you configure in a traffic control profile define the following characteristics for the priority group:

  • guaranteed-rate—Minimum bandwidth, also known as the committed information rate (CIR). Each priority group receives a minimum of either the configured amount of absolute bandwidth or the configured percentage of bandwidth. The guaranteed rate also determines the amount of excess (extra) port bandwidth that the priority group can share. Extra port bandwidth is allocated among the priority groups on a port in proportion to the guaranteed rate of each priority group.

    Note: In order for the transmit-rate option (minimum bandwidth for a queue that you set using scheduler configuration) to work properly, you must configure the guaranteed-rate for the priority group. If a priority group does not have a guaranteed minimum bandwidth, the queues (forwarding classes) that belong to the priority group cannot have a guaranteed minimum bandwidth.

    Note: Include the preamble bytes and interframe gap bytes as well as the data bytes in your bandwidth calculations.

  • shaping-rate—Maximum bandwidth, also known as the peak information rate (PIR). Each priority group receives a maximum of the configured amount of absolute bandwidth or the configured percentage of bandwidth, even if more bandwidth is available.

    Note: Include the preamble bytes and interframe gap bytes as well as the data bytes in your bandwidth calculations.

  • scheduler-map—Bandwidth and scheduling characteristics for the queues, defined by mapping forwarding classes to schedulers. (The queue scheduling characteristics represent amounts or percentages of the priority group bandwidth, not the amounts or percentages of total link bandwidth.)

Note: Because a port can have more than one priority group, when you assign resources to a priority group, keep in mind that the total port bandwidth must serve all of the queues associated with that port.

For example, if you map three priority groups to a 10-Gigabit Ethernet port, the queues associated with all three of the priority groups share the 10-Gbps bandwidth as defined by the traffic control profiles. Therefore, the total guaranteed-rate value of the three priority groups should not exceed 10 Gbps.

Configuring a Traffic Control Profile

Step-by-Step Procedure

This example describes how to configure a traffic control profile named san-tcp with a scheduler map named san-map1and allocate to it a minimum bandwidth of 4 Gbps and a maximum bandwidth of 8 Gbps:

  1. Create the traffic control profile and set the guaranteed-rate (minimum guaranteed bandwidth) to 4g:
  2. Set the shaping-rate (maximum guaranteed bandwidth) to 8g:
    [edit class-of-service]
    user@switch# set traffic-control-profiles san-tcp shaping-rate 8g
  3. Associate the scheduler map san-map1 with the traffic control profile:
    [edit class-of-service]
    user@switch# set traffic-control-profiles san-tcp scheduler-map san-map1

Verification

Verifying the Traffic Control Profile Configuration

Purpose

Verify that the traffic control profile san-tcp has been created with a minimum guaranteed bandwidth of 4 Gbps, a maximum bandwidth of 8 Gbps, and the scheduler map san-map1.

Action

List the traffic control profile using the operational mode command show configuration class-of-service traffic-control-profiles san-tcp:

user@switch> show configuration class-of-service traffic-control-profiles san-tcp
scheduler-map san-map1;
shaping-rate percent 8g;
guaranteed-rate 4g;

Published: 2012-07-31