Algorithm A: VCShare and ExcessFairShare

Next: Algorithm B: ExcessFairShare/OverloadUp: The Switch SchemesPrevious: Overload Based Algorithm: General

Algorithm A: VCShare and ExcessFairShare

The ExcessFairShareterm is defined as follows:

$\begin{displaymath}ExcessFairShare(i) = \frac{w_i (A - \mu)}{\sum_{j=1}^n w_j} \end{displaymath}$

This divides the excess available bandwidth ( $A - \mu$ ) proportional to the weights w(i).

The activity level for a given VC is defined as follows:

$\begin{displaymath}AL(i) = minimum \left ( 1, \frac {{\mbox SourceRate}(i)- \mu_i} {ExcessFairShare(i)} \right ) \end{displaymath}$

The activity level can be used to accurately estimate the effective number of VCs [ 3]. We extend this notion to the weighted case by multiplying the weight function with the activity level of the ExcessFairShareterm. Therefore the ExcessFairShareis:

$\begin{displaymath}ExcessFairShare(i) = \frac{w_i AL(i) (A - \mu)}{\sum_{j=1}^n w_j AL(j)} \end{displaymath}$

In Algorithm A, the Excess_ERis calculated based on the VCShareand the ExcessFairShareterms.

End_of_Interval_Accounting():
foreach VC i

AL(i)	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle minimum \left ( 1, \frac {{\mbox SourceRate}(i)- \mu_i} {ExcessFairShare(i)} \right )$	(20)
ExcessFairShare(i)	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \frac{\mbox{(Target ABR Capacity)} w_i } {\sum_{j=1}^n w_j AL(j)}$	(21)

endfor

Calculate_Excess_ER():

$\displaystyle \mbox{VCShare}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \frac{SourceRate(i) - \mu_i}{z}$	(22)
$\displaystyle \mbox{Excess\_ER}$	$\textstyle \mbox{$\leftarrow$ }$	$\displaystyle \mbox{Max (ExcessFairShare(i), VCShare)}$	(23)

Next: Algorithm B: ExcessFairShare/OverloadUp: The Switch SchemesPrevious: Overload Based Algorithm: General

Bobby Vandalore
1998-07-22