topic Re: Priority in PAN-QoS in General Topics

Priority in PAN-QoS

nanukanu — Thu, 06 Oct 2016 07:13:37 GMT

Hi,

When you are configuring QoS, it's possible to define more than one profile, and in this profile put 'til 8 Class defined.

When you apply over the egress interface, it's possible to add this Class based over an source Subnet.

Here is my question, what "priority use" or what is the behaviour if over the same interface applies in ex:

From Subnet 1.1.1.0/24 ---- Profile A - Class2 - Priority Real-Time

From Subnet 2.2.2.0/24 ---- Profile B - Class2 - Priority Real-Time

How are evaluated?

As far I understand, in order to enqueue, the order are: 1. Class, 2.Priority. What role takes QoS Policies here?

thanks!!!

Regards!

Re: Priority in PAN-QoS

reaper — Thu, 06 Oct 2016 07:46:55 GMT

you can assign different profiles to different subnets, but the sum of all profiles will need to comply with the total bandwidth available

IO priority wise, both classes will share the same hardware pool, so if both classes are real-time, they will gain preference over other classes with lower priority, and will need to share their own priority (so it's possible they fight over it)

Re: Priority in PAN-QoS

ilnanu — Thu, 06 Oct 2016 13:45:03 GMT

Hi Reaper,

Many thanks for you response.

In case of same class + same priority, what is the tie-braker choosed to priorize one of other?

The QoS Policies play some role on this decisions?

Regards!!

Re: Priority in PAN-QoS

reaper — Thu, 06 Oct 2016 13:59:38 GMT

class doesn't really matter since you could set class 8 to real-time

Real-time priority has it's own queue but if contention occurs for 2 sessions in the same priority, FIFO would apply

normally the lower priority sessions would get discarded in favor of the higher priority

Re: Priority in PAN-QoS

ilnanu — Thu, 06 Oct 2016 15:18:22 GMT

Hi Reaper,

But, if in the same profile Class1 has Normal and Class8 has Real-Time, isn't prioritaty Class1?

Re: Priority in PAN-QoS

reaper — Thu, 06 Oct 2016 21:25:23 GMT

Hi @ilnanu

no, in your example class8 has priority because it has real-time (what's under the 'priority' column is what counts)

the 'class' is more like a name (like A,B,C,...) ,rather than a designation of priority. it's just easier to categorize your priorities with a numbered class ( the default profile goes class1 realtime to class8 low, but you could easily switch that order around or mix it up, whatever makes more sense to you)