The ANSI X3T9 committee has made a decision on how to pass Fibre Distributed Data Interface traffic over unshielded copper cabling after the two warring camps agreed a truce and placed a joint proposal before the committee. Previously, the Cabletron Systems Inc-led group had backed the transmission technology called NRZI, while that faction headed by Sunnyvale, California-based Crescendo Communications Inc preferred the more complex MLT-3. That the joint scheme relies on MLT-3 means that Crescendo has won the argument, although Cabletron is contributing some technology, including digital shifting, a technique to combat transmission errors that occur in the unshielded medium. The development of the CDDI standard has proved slower than expected since Hewlett-Packard Co presented the results of tests on the competing technologies last month. But the committee asked for more details and it was feared that a ballot of members set for this August would be missed. It was in the face of damaging delays that the deal was struck and David Palmer-Stevens, Cabletron’s European marketing manager, says that acceptance should put the standard back on track designers have something firm to work with and observers expect full ratification next spring. Nonetheless, Cabletron’s own product development has been hit by the technology switch, with launches pushed back by about three months to early next year. It’s too early to say how much CDDI Copper Digital Data Interface adaptors will cost, but Palmer-Stevens suggests that $1,000 is a plausible ball-park figure. He predicts dramatic reductions in FDDI prices.
