Multicast cell scheduling protocol

Abstract

A method of facilitating the scheduling of a first multicast request signal of a series of multicast request signals is disclosed, wherein the first request signal is generated to enable the transmission of a multicast data cell by a source port processor to at least one destination port processor. In a preferred embodiment of the invention, the first request signal is received by a roster storage chip associated with a scheduler subsystem. The first request signal has associated therewith a multicast label of a first value and is adapted to schedule transmission of the first multicast cell to the at least one destination port processor at a first time. A roster of the at least one destination port processor to which the first multicast cell is destined is then generated. A dependence distance associated with the first request signal is determined. The dependence distance comprises the numerical value of the difference between a current multicast cell number (CMCN) and a previous multicast cell number (PMCN). The roster and the dependence distance are transmitted to one of the at least one scheduler chips, such transmission causing the roster and the dependence distance to occupy a second tail entry slot of a second circular buffer associated with the one of the at least one scheduler chips. The second tail entry slot has associated therewith a first multicast table index (MTI) comprising a numerical value. The scheduler chip further has associated therewith a head entry slot having associated therewith a second MTI comprising a numerical value. A first numerical parameter comprising the numerical sum of the dependence distance and the first MTI is determined. If the first numerical parameter is higher in value than the second MTI, the first request signal is arbitrated.