| 摘要 |
A flow control mechanism is presented that provides XON/XOFF flow control for each virtual channel in an interswitch link. The entire interswitch link remains under standard Fibre Channel BB_Credit flow control. Each virtual channel in the interswitch link can submit data to multiple ports in the downstream switch. The XOFF status of each port in the downstream switch is maintained in an XOFF mask. A mapping between each virtual channel and all ports accessible through the virtual channel is then applied to the XOFF mask, which determines the XOFF status of each virtual channel. An XOFF signal is generated by the downstream switch on a change in XOFF status for any virtual channel. The preferred XOFF signal is one or more Fibre Channel primitive containing the status for every virtual channel. Each primitive sends duplicate XOFF information, and always ends in negative running disparity.
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