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Scheduler per unit basis versus Scheduler per physical interface

‎10-12-2017 08:07 PM

Hi everyone,


Juniper COS is way complicated compared to other vendors I have worked witjh in past.

I am going to keep pushing until i get COS down.


A few questions on scheduler:



JR2> show configuration class-of-service schedulers
EF10 {
    transmit-rate {
        percent 10;
    transmit-rate {
        remainder {


1)Let say above the CKT is 100M there is no other traffic just EF only , in this case EF is still limited to 10M or it can use all the availabe bandidth?



2) If we add Priority strict high to EF above, is traffic still limited to 10M?


3)  Let say we have  ge-0/0/0 connected to many many provider using logical interfaces:

ge-0/0/0 unit 10---CIR 10M

ge-0/0/0 unit 20--CIR  10 M


4)We have defined all our COS (  forwarding class, classifiers,  one scheduler map A ), both CKTS have identical COS requirements.

What is the difference between appying scheduler map A  to the whole  physical port ge-0/0/0 versus to logical units 10 and units 20 individually?


5)  Does  applying scheduler per unit basis give us egress queue stats using "show interface queue ge-0/0/0.10" not sure if this command is valid?



Thanjs and have a nice weekend!!



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Accepted by topic author sarahr202
‎10-13-2017 07:14 AM

Re: Scheduler per unit basis versus Scheduler per physical interface

[ Edited ]
‎10-13-2017 01:48 AM

ad 1) It is limited to 10Mbps. It works as a shaper.

ad 2) Yes, it is limited. As a matter of fact it is recommended to always limit the bandwidth on strict-high priority queues. Otherwise it can cause starvation of lower priority queues.

ad 3,4)
scheduler-map applied to physical interface -> single scheduler map
scheduler-map applied to physical interface + per-unit-scheduler -> same scheduler map for each logical unit
scheduler-map applied per logical unit + per-unit-scheduler -> can have different scheduler maps for different logical units

ad 5) yes

If you think it's complicated try to read through CoS chapter in Juniper MX Series Orelly book 🙂 can give a headache.

Regards, Wojtek

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Re: Scheduler per unit basis versus Scheduler per physical interface

‎10-13-2017 07:17 AM

Thanks Wdudys for all your help,  I am going to take baby steps , do not want to get burned out.

Have a nice day!!!