Impact of HPPI and fibre channel standards on data delivery

Two ANSI X3T9.3 standards activities are discussed. HPPI (high performance parallel interface) is a simple electrical point-to-point device that is implementable at either 100 or 200 MB. A HPPI channel is unidirectional; only a few return wires are used for flow control by the destination. There are no means for retransmitting after error, although the data is protected by adequate parity and longitudinal redundancy bits. Error bursts are delivered with status=error, or optionally dropped in the bit bucket, and any corrective action must be initiated by an upper-layer protocol. Thus, HPPI provides a datagram service. The fiber channel standardization project is a direct response to the need to extend the range of SCSI, IPI, and HPPI, all of which are electrical systems. Accordingly, the fiber channel standards working group established a goal of defining implementations that will accommodate SCSI, IPI, and HPPI within a common compatible lower-level set of protocols. It appears that other important transmission protocols can be modulated/carried on the fiber channel; examples are BlockMux channel and FDDI.<>