Method and apparatus for using multiple fifos to improve flow control

Abstract

A method and associated apparatus for using a primary FIFO and one or more secondary FIFOs in parallel to simplify flow control and routing in packet communication operations wherein at least one FIFO (buffer) is associated with each of a plurality of receiving nodes or components within a receiving node. The present invention applies received packets simultaneously to a primary FIFO and to all associated secondary FIFOs in the receiver of a packet communications link. After receipt of a packet, the packet is removed from any secondary FIFOs which correspond to receiver nodes or components to which the packet was not routed. For all receiving nodes or components to which the packet was routed, if the packet was stored in each associated secondary FIFO without overflow, then the packet is also purged from the primary FIFO. If any secondary FIFO overflowed by storage of the received packet, then the packet is purged from the overflowed FIFO and the packet remains stored in the primary FIFO for further processing. Flow control signals are generated and applied to the transmitting source as required in accordance with the status of the primary FIFO. The secondary FIFOs are not directly relevant to flow control logic. The receiving component corresponding to each secondary FIFO locates the next packet for processing by inspecting the associated secondary FIFO as well as the primary FIFO if the secondary FIFO overflowed. These methods and apparatus simplify flow control and routing control in packetized communication receivers.