A method is disclosed for maintaining a table of recent accesses for each port for use in predicting whether a request for data from a source device is likely to be sent to a high speed or low speed destination device. The table of recent accesses lists every source device attached to that port and the speed of the destination device with the most recent access to each source device. When an OPN primitive is received at the source port, the source device is identified and used with the table of recent accesses to predict whether the destination device is likely to be high speed or low speed, and ultimately whether to send data from the source device or reject the request.