Re: EX 200 and Scheduler priority

Yes you can, you have to configure queues shaping to avoid lower priority queues starvation.

An example borrowed from: https://www.juniper.net/documentation/en_US/release-independent/nce/topics/example/cs1-qos-configuring.html

[edit class-of-service]
user@cs-4200-ab1# set schedulers control-network-sched shaping-rate percent 5 
user@cs-4200-ab1# set schedulers control-network-sched buffer-size percent 5
user@cs-4200-ab1# set schedulers control-network-sched priority strict-high 
user@cs-4200-ab1# set schedulers control-user-sched shaping-rate percent 1 
user@cs-4200-ab1# set schedulers control-user-sched buffer-size percent 5
user@cs-4200-ab1# set schedulers control-user-sched priority strict-high 
user@cs-4200-ab1# set schedulers voice-network-sched shaping-rate percent 5 
user@cs-4200-ab1# set schedulers voice-network-sched buffer-size percent 5
user@cs-4200-ab1# set schedulers voice-network-sched buffer-size exact
user@cs-4200-ab1# set schedulers voice-network-sched priority strict-high 
user@cs-4200-ab1# set schedulers voice-user-sched shaping-rate percent 1 
user@cs-4200-ab1# set schedulers voice-user-sched buffer-size percent 5
user@cs-4200-ab1# set schedulers voice-user-sched buffer-size exact
user@cs-4200-ab1# set schedulers voice-user-sched priority strict-high
user@cs-4200-ab1# set schedulers video-sched transmit-rate percent 20
user@cs-4200-ab1# set schedulers video-sched buffer-size percent 20
user@cs-4200-ab1# set schedulers video-sched priority low
user@cs-4200-ab1# set schedulers mission-critical-sched transmit-rate percent 40
user@cs-4200-ab1# set schedulers mission-critical-sched buffer-size percent 40
user@cs-4200-ab1# set schedulers mission-critical-sched priority low
user@cs-4200-ab1# set schedulers be-sched transmit-rate remainder
user@cs-4200-ab1# set schedulers be-sched buffer-size remainder
user@cs-4200-ab1# set schedulers be-sched priority low

You can find an explanation of EX priority scheduling here:
https://www.juniper.net/documentation/en_US/junos10.0/topics/concept/cos-ex-series-schedulers-understanding.html#jd0e65

Regards, Wojtek