From: Sridhar Vaidyanathan (vsridhar83@gmail.com)
Date: Sat Mar 07 2009 - 18:52:45 ARST
Hi,
I have trying to learn about the 3560 QoS mechanism but does not seem to
understand the values given in qset. So far I have the following
understanding of the qset values. Please correct me if I am wrong.
Queueset: 1
Queue : 1 2
3 4
buffers : 25 25 25
25
threshold1: 100 70 100 40
threshold2: 100 80 100 100
reserved : 50 100 50
100
maximum : 400 100 400 100
The buffer values are actual percentage allocation of buffer space. In the
above case, the buffer space is equally divided to all queues.
The threshold value is the percentage from the buffer percentage of 25% of
individual queue. If that is the case then how are we able to put a value of
something greater than 100. What does it infer?
The reserved value is a percentage out of the buffer percentage of 25%. In
case of Queue 1 that means, the buffer space allocated actually to the queue
is 50% of 25% buffer space and the remaining is allocated to common pool.
A reserved value of 100% would mean that the no allocation is done to common
queue at all and the queue utilizes all the buffer space allotted to it that
is 25% of the total buffer space.
I did not quite understand what the maximum value would mean considering the
fact that the value can go upto 3200. In the above example, Q1 and Q3 are
giving 50% percent of their reserved buffer space to common pool and Q2 and
Q4 are utilizing the entire reserved space. That leaves 50% of buffer space
from Q1 and 50% of buffer space from Q3 in common pool.
Can you please explain me in detail as I am unable to understand the concept
behind it.
Regards,
Sridhar.
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