Network switching system supporting guaranteed data rates

Abstract

In a cell switching network, a method of buffering cells in a switch assigns guaranteed buffer space per time interval T to individual virtual connections (VCs). In each of successive periods of time, the individual VCs are allocated available buffer space up to their guaranteed buffer space. After the VCs are served their guaranteed data rates, and within the remaining time of each period, excess buffer space is allocated to individual VCs. In a preferred embodiment, cells are stored in a shared first-in-first-out (FIFO) buffer which serves plural VCs. A cell count is maintained for each VC, and is incremented for each corresponding incoming cell. Cell counts are decremented according to a round robin scheme, no lower than some negative limit, independent of the actual VC with which the outgoing cell is associated, allowing the VC to make up some bandwidth later for an earlier period of non-use. When a cell count for some virtual connection is above a connection threshold, incoming cells associated with the virtual connection are blocked from storage in the buffer. In an alternate embodiment, cells are buffered in queues where there is one queue per VC.