From: Bob Arthurs (bob_arthurs@hotmail.com)
Date: Fri Sep 16 2005 - 14:12:58 GMT-3
I wonder if someone can help me with some QoS calculations (it's too much
for my brain!)...
When you configure WRED on CIsco routers I know it is possible to configure
the exponential weighting constant (though I know it's normal to leave it at
its default of 9). Anyway, the exponential weighting is obviously related to
the average queue size as follows:
average= (old_average * [1-2^-n]) + (current_queue_depth * 2^-n)
where 'n' is the exponetial weighting constant.
[see page 434 of Cisco Press DQOS Exam certification guide (old edition) for
this equation]
You can adjust 'n' as follows (from CCO):
2^-n = 10/bandwidth
where bandwidth = queue bandwith / (MTU*8).
My question is: how can you work out 'n' if you know the bandwidth using the
2^-n = 10/bandwidth equation. What I mean is n= what?? I need a simplified
equation....
I am sure this is a very easy question for someone with a little knowledge
of math, but it's too much for me (I have long since forgotten all my
math!), so I'd really appreciate some help :)
Thankyou very much in advance.
This archive was generated by hypermail 2.1.4 : Sun Oct 02 2005 - 14:40:15 GMT-3