Change in Class of Service Syntax between 12.3 and recent versions?

‎05-28-2019 02:05 PM

Afternoon - JNCIE hopeful here


I have been preparing for some time now but have heard some distrubing rumors that there are significant differences between CoS configuration in current versions of Junos and the version used in the Lab (12.3). I am using vMXs on 15.1 (oldest available) in my lab presently and am hoping that this is an adequate representation of software in the lab.

Is this correct? If there are differences, can you suggest a version or platform that uses the same syntax as 12.3? such as vSRX at x version, etc.

thank you!

Accepted by topic author byron.moore
‎10-31-2019 10:54 AM

Re: Change in Class of Service Syntax between 12.3 and recent versions?

‎05-28-2019 08:36 PM

Hi Byron,


You should be alright, the options under "ethernet-switch-options" are now available under "switch-options".   Just review the ELS vs Non-ELS changes here:


I'd used vSRX on 12.1X47-D10 and didn't have major syntax differences last year.


Hope this helps.




If this solves your problem, please mark this post as "Accepted Solution."
Kudos are always appreciated :).




Re: Change in Class of Service Syntax between 12.3 and recent versions?

‎05-30-2019 11:43 AM

I am afraid that you need to do more research/study before you ask this question.


The concept of CoS is pretty much the same on all junos all across different platforms, including M/MX/T/ACX/EX/QFX/SRX. But the syntax can be different. If you well understand concept of classification / scheduler / policer / rewrite / shape, I believe you won't get distracted by any "rumor". Because, at the end of the day, CoS is pretty simple from configuration perspective.


However, CoS is very platform dependant. On what platform are you trying to implement CoS? For example on MX. It may also depend on the type of card if you are using complicated technologies like ingress in queueing, hierachy scheduler. Otherwise, it's pretty common. 


I'd suggest you to find some example on Tech Pub based on what platform you are using to implement CoS (Most of them should be working for recent junos, eg 15.1 later), if any specific error pops up, we can look into it.


Mengzhe Hu