A switch queue predictive protocol (SQPP) includes a packet switching
system including: a switch fabric having a cross-point switch, and a
plurality of line cards, each coupled to the switch fabric. A cross-point
buffer is located at each cross-point of the cross-point switch. The
switch fabric also includes a plurality of actual available queue space
tables (AAQSTs), each identifying the actual queue space available in a
row of the cross-point buffers. Each of the line cards includes an input
buffer, an output buffer, and a predicted available queue space table
(PAQST) identifying predicted queue space available in a corresponding
row of the cross-point buffers. Packet information is transmitted from a
source line card to the switch fabric only if available queue space is
predicted by the corresponding PAQST. The switch fabric uses the AAQST to
update the PAQST after packet information is transmitted to a destination
line card.