From: Salau,Olayemi (Olayemi.Salau@southampton.gov.uk)
Date: Thu Jan 18 2007 - 10:05:25 ART
>From the principle of mathematics, I believe you're right.
One thing we need to understand is that Bc is the normal token bucket
which can usually be derived from the formula CIRxTc/1000 (where Tc is
in milliseconds)
Bc literally means the number of packets in bits that can go through in
Tc seconds of time interval, Whereas CIR is the number of packets in
bits that can be transferred in 1 second.
But if we're bursting, this means we're using extra bandwidth on the
link, ie. (AR-CIR) for your extra credits. So if you're bursting up to
an EIR value of say 300kbps, this value is what you should use as AIR
for your Be Calculation. This literally gets the difference between the
CIR and EIR and that will give you another value say BeIR(this is my own
invented value). BeIR is literally the amount of packets in bits that
can go through the interface in a time interval of 1seconds. Be itself
is amount of packets in bits that can go through in time interval period
of Tc seconds.
So, if the question states a burst speed lower than CIR; well a bit
unusual I would say, but interpreting this will mean, CIR is zero, ie.
You're not using up to the committed rate to calculate your Be. (Be =
(AR-CIR)xTc/1000 same thing as BeIRxTc/1000 with BeIR=(AR-CIR))
In this case I would say BeIR=AR-CIR=EIR-CIR=EIR-0=EIR; putting CIR to
be zero. This is because your EIR is not up to CIR. This is my own
interpretation from mathematical point of view, don't know what others
might think, but I would say it's a valid interpretation and an Unusual
situation.
Many Thanks
This archive was generated by hypermail 2.1.4 : Thu Feb 08 2007 - 23:46:57 ART