Unified network cell scheduler and flow controller

A segmentation and reassembly (SAR) controller for controlling the flow of fixed length communication cell over a communication path and channel of a communication network, the SAR controller comprising:

• a system bus interface for coupling to a system bus and communicating to a host system;
• a storage controller, for coupling to a rewritable storage having scheduled times and virtual communication channel parameters data stored therein, addressing the rewritable storage, and reading the data from and writing the data into the rewritable storage;
• a network output interface for coupling to a transmission cabling of the network;
• a network input interface for coupling to receiving cabling of the network;
• a segmenter, coupled to the system bus interface, the memory controller, and the network output interface, for segmenting data into prioritized fixed length communication cells;
• a scheduler coupled to the segmenter and the memory controller, having a sorter and a microcode engine for sorting and scheduling the prioritized fixed length communication cells for transmission out to the network based on the scheduled times and virtual communication channel parameters, said microcode engine computes the next scheduled time by adding the current transmission time with the modified parameter of the allowed cell period to generate an ideal next scheduled time, said modified parameter being generated by a rate adjustment program, said ideal next scheduled time being used to compute an expiration time and a maturation time;
• a reassembler, coupled to the system bus interface, the memory controller, and the network input interface, for removing the header from the prioritized fixed length communication cells and reassembling them into usable data, the reassembler further comprising:
• a DMA controller coupled to the system bus interface for communicating user data onto the system bus, and
• a network feedback logic coupled to the network input interface for reading the prioritized fixed length communication cells received from the network and adjusting the sorting and scheduling of the prioritized fixed length communication cells by the scheduler.

A method of prioritizing and scheduling the flow of fixed length communication cells over a communication channel of a communication network, the steps comprising:

• a) computing a priority value for a fixed length communication cell based on communication channel parameters, said priority value being an expiration time computed by adding a cell delay variation tolerance to an ideal next scheduled time, said ideal next scheduled time being computed by adding a modified allowed cell period to a current transmission time, said modified allowed cell period being computed by a rate adjustment program;
• b) storing the priority value and an identifier of the fixed length communication cell into a rewritable storage unit;
• c) sorting on the priority value of the fixed length communication cell to determine the cell having the highest priority;
• d) selecting the fixed length communication cell having the highest priority for transmission over the communication channel of the communication network;
• and
• e) repeating steps (a) through (d).