Selling bandwidth to customers is quite easy but to maintain the speed is such a lobotomize work. Customers always mull to get the same speed whatever they subscribed for bandwidth. But its really hectic job to render the same what was commited to customer. Sales guys always sell the bandsith with respective to the speed. Lets take one example when the bandwidth of 10 Mbps was sold to customer then it doesnot mean customer would get 10 Mbps per/second but customers always demand the same. In fact if we do the calculations as per the given formula we would be able to get to know how much commited burst can be given to customer per interval.
TC=Commited Time Interval
CIR=Commited Information Rate
CIR means total number of bits that will be flown in a second or you can say the shaped rate.
TC=Commited time interval per burst.BC=Commited burst whcih can be sent in particular interval.
BC=Commited burst whcih can be sent in particular interval.
In Cisco IOS a second is divided into 8 time intervals of 125ms each(125*8=1000ms or 1 sec). If you want to provide 64000 bits or 64Kbps to a customer then you need to calculate the burst for that because that will be the maximum value which will occue in one time interval of 125ms. So CIR=64000 Tc=125ms Now calculate Bc which will be equals to (125/1000*64000) = 8000 bits. The result is lucid, it means in a sinle interval customer cannot pump more than 8000 bits per interval when he owns spped of 64Kbps. This is what we need to make clear to customer before selling the bandwidth.