Overload Based Algorithm: General Structure

The four different switch schemes have the following common algorithmic structure. They differ in the manner in which the feedback rate is calculated and accounting.

$\displaystyle \mbox{Total ABR Capacity}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mbox{Link Capacity} - \mbox{VBR Capacity}$
		$\displaystyle - \sum_{i=0}^n \mbox{min}(SourceRate(i),\mu_i)$	(14)
$\displaystyle \mbox{Target ABR Capacity}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle Fraction \times \mbox{Total ABR Capacity}$
$\displaystyle \mbox{Input Rate}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mbox{ABR Input Rate} - \sum_{i=0}^n min (SourceRate(i),\mu_i)$
z	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \frac{\mbox{Input Rate}}{\mbox{Target ABR Capacity}}$	(15)
$\displaystyle \mbox{\bf End\_of\_Interval\_Accounting()}$			(16)

$\displaystyle \mbox{Excess\_ER}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mbox{\bf Calculate\_Excess\_ER()}$	(17)
$\displaystyle \mbox{ ER}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mu_i + \mbox{Excess\_ER}$	(18)
$\displaystyle \mbox{ER\_in\_RM\_Cell}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mbox{Min (ER\_in\_RM\_Cell, ER, Target ABR Capacity)}$	(19)

The key steps which differentiate the algorithms are the procedures End_of_Interval_Accounting()and Calculate_Excess_ER().