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How to apply a pre-defined COS template on the EX series Switches



Article ID: KB15119 KB Last Updated: 04 Mar 2017Version: 2.0
JUNOS class of service (CoS) provides you a pre-defined template to divide traffic into classes and offers various levels of pre-defined throughput and packet loss if congestion occurs. This allows packet loss to happen according to pre-configured rules that are configured by the user.


The EX series Switch provides the user a pre-defined COS template to assist with the COS configuration for VoIP applications on the EX switch. The ezqos-voip template can be edited by the user.

There are 4 forwarding classes (EC) in ezqos-dscp-classifier:
  • ez-qos-video-fc mapped to queue 4
  • ez-qos-voice-fc mapped to queue 5
  • ez-qos-best-effort mapped to queue 0
  • ez-qos-control-fc mapped to 7

These Forwarding Classes (FC) have the following DSCP matching values:
  • ez-qos-voice-fc – 46
  • ez-qos-video-fc – 34
  • ez-qos-control-fc –24, 26, and 48-63
  • ez-qos-best-effort – 0-47

The EZQoS VoIP template is stored in /etc/config/ezqos-voip.conf.

To load and apply the template:
  •  Load the ezqos configuration
user@switch# load merge /etc/config/ezqos-voip.conf
  • Apply the EZQoS group (ezqos-voip):
user@switch# set apply-groups ezqos-voip
  • Apply the DSCP classifier (ezqos-dscp-classifier) to a Gigabit Ethernet interface (ge-0/0/0):
[edit class-of-service interfaces]
user@switch# set ge-0/0/0 unit 0 classifiers dscp ezqos-dscp-classifier
  • Apply the scheduler map (ezqos-voip-sched-maps) to a Gigabit Ethernet interface (ge-0/0/1):
[edit class-of-service interfaces]
user@switch# set ge-0/0/1 scheduler-map ezqos-voip-sched-maps

To verify Class of Service (CoS) from CLI use the "show class-of-service <cmd>" commands.

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