! ! As data rates increase, low-cost optical-fiber links play an increasingly significant
role in LANs for extending the length of links beyond what can be achieved with
copper media, while meeting the full range of electromagnetic emission and susceptibility requirements for networks.
The 100VG-AnyLAN standard defines a serialized interface with a 120-megabaud
signaling rate for STP and multimode optical-fiber links. The standard defines two
optical-fiber link length specifications, which allow the use of low-cost 850-nm
technology for 500-m building backbones (this is the same technology used in the
existing IEEE 802 standard CSMA/CD 10Base-F and 802.5J token-ring links) and
1300-nm technology for 2-km campus backbone links.
Fig. 1 shows the new Hewlett-Packard low-cost industry-standard optical transceiver package. This small package is 1 inch wide and 1.5 inches long and has a
duplex SC optical connector on the front and a 1-by-9 row of electrical pins at the
rear. HP transceivers HFBR 5106/5107 meet the two 100VG-AnyLAN link length
standards and allow interchanging link technology in the same printed circuit board
footprint. The transceivers are also available with AT&T ST optical connectors to
address the large installed base having ST connectors for building and campus
backbones.
Del Hanson
Principal Engineer, Fiber-Optic
Networks and Standards
Optical Communications Division
Fig. 1. HP optical transceiver.
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