[RPRWG] Decoupling the service classes
All,
Presentations at last week's meeting indicated a shared
(by at least a few of us) concern towards the interactions
between classB/C and classA traffic guarantees.
To assist with thoughts in this area, I have attached a
short description that (I believe) shows the "tough"
scenario and describes how it could be handled. Its
an overview only, but a useful starting point before
jumping into the equations&simulations swamp.
The key points are as follows:
a) Downstream shaper scoping:
1) Must throttle classB&classC (not just classC).
2) Must throttle STQ, as well as add traffic.
b) Downstream shaper rates:
1) If lightly congested downstream, the throttle
limits would support downstream subclassA0 rates.
2) If highly congested downstream, the throttle
limits would support downstream classA rates
(subclassA0 plus subclassA1).
c) ClassB should have precedence over classC.
As is typical with prioritized classes, the difficult
problems are not fairness within a class, but sustaining
fairness while supporting prioritization between classes.
DVJ
David V. James
3180 South Ct
Palo Alto, CA 94306
Home: +1.650.494.0926
+1.650.856.9801
Cell: +1.650.954.6906
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Base: dvj@xxxxxxxxxxxx
dvjFairness2003May26.pdf