a transfer controller with hub and ports is viewed as a communication hub between the various locations of a global memory map . a request queue manager serves as a crucial part of the transfer controller . the request queue manager receives these data transfer request packets from plural transfer requests nodes . the request queue manager sorts transfer request packets by their priority level and stores them in the queue manager memory . the request queue manager processes dispatches transfer request packets to a free data channel based upon priority level and first - in - first - out within priority level .