System and method for efficient initialization of a ring network

摘要

A Fibre Channel network is provided with an efficient implementation of the loop initialization process. In one embodiment, the network comprises nodes coupled by unidirectional serial communications links in a ring topology. The nodes typically include a serial communications transceiver, a transmit controller, a receive controller, and a memory unit. The serial communications transceiver operates to drive transmit signals on the outgoing serial communications link and to buffer receive signals from the incoming serial communications link. The memory unit includes transmit and receive buffers that are coupled to the transceiver via transmit and receive controllers. One or more of the nodes may also include a control register having an "autoswap" bit. The autoswap bit is initially reset to 0 when the node enters the initialization mode. When the autoswap bit is set to 1, the transmit and receive buffers exchange roles after every data frame so that received initialization data frames stored in the receive buffer are retransmitted by the transmitter controller. When the autoswap bit is not set, a comparison between the original transmitted initialization data frame and the received initialization data frame is performed, and if it is determined that the received initialization data frame is less than the original transmitted initialization frame, the autoswap bit is set. Otherwise a check is made to determine if the two frames are equal, in which case the node determines that it has received its original transmitted initialization data frame and assumes the role of Loop Initialization Master. If the received initialization data frame is neither less than or equal to the original frame, then the original initialization data frame is retransmitted, and the cycle is repeated with the next received frame. This implementation advantageously reduces the retransmission latency of nodes in the loop and thereby reduces the propagation delay of the smallest initialization data frame around the loop, resulting in a smaller loop initialization time.