Printer Friendly

On-premises utility is also learning lab.


Lehigh University, Bethlehem, Pa., has instlled a fiber LAN that's a communications utility for recently refurbished Mohler Laboratory.

The LAN also provides ample opportunities for graduate students to experiment with networking concepts.

The Mohler Laboratory, a four-stroy building that once was a community center, now houses multidisciplinary research programs involving advanced manufacturing techniques.

The facility has:

* a Computer Integrated Manufacturing (CIM) Lab,

* Robotics Lab,

* Intelligent Systems Lab,

* and Center for Manufacturing Systems Engineering.

The buildings's fiber network is operating initially at 830 nanometers and 10 Mb/s.

Prof. Richard T. Denton suggested the on-premises LAN during planning meetings for the building refurbishment.

He was with Bell Labs for 30 years before joining the university staff.

"This refurbishment was a major undertaking, stripping the building down to its shell." he says.

"The best time to put in a communications utility is before the walls go back up.

"Otherwise, network installations can be costly or unattractive.

"A fiber-optic network doesn't cost much more than other technologies in terms of materials and labor but offers a great deal mor capacity, security, and flexibility."

No EMI Threat

Fiber is also immune from ground loops and electromagnectic interference (EMI).

The lab houses heavy industrial machinery that can generate high levels of EMI.

Current uses for the network include resource sharing, workstation communications, word processing, and file management.

The network doubles as a learning lab for electrical engineering graduates and undergraduates.

Fiber can simultaneously communicate several network protocols.

The network now operates under Ethernet but Denton plans to implement FDDI subnetworks soon, using wavelength division multiplexing.

"The industrial and manufacturing engineers may want to use the MAP protocol developed by General Motors," he says.

The fiber backbone network in the lab primarily consists of transceivers and passive fiber components (most of which came from AMP Inc.).

At the user end, fiber multimode cables terminate in wall and ceiling outlets throughtout the four-story building.

Rigid Shroud

AMP FSD (Fixed Shroud Duplex) connectors provide low loss and a rigid, protective shroud that guards against mishandling or mismating.

Lehigh measured an average connector reflection loss of 28dB.

This low reflection-loss level permits network transmission rates up to 300 Mb/s and higher before the connectors begin to limit system performance.

Lehigh assembles fiber jumper cables for the connection between the wall outlets and the user's PC or workstion.

One end of the fiber jumper connects to the wll outlet with the AMPFSD connector> the other end connects with two AMP ST type connectors to a transceiver board in the PC. The transceiver performs the optical/electronic conversion in both directions.

The fiber used in the Mohler Building was 62.5/125.

The cable runs form wall outlets up behind the walls and along raceways above the dropped ceiling.

Cables for each floor terminate in a communications closet that houses AMP 16 X 16 star couplers and a file server.

The star coupler is a passive optical component that evently distributes the signal from any one of its 16 inputs to all 16 outputs. The star coupler acts as an optical bus for each subnetwork.

Bus for Reliability

Lehigh close a bus topology to increase system reliability> failures to individual nodes or subnetworks have minimal effect on the overall network.

Each of the four floors has multiple subnetworks.

The third floor, for example, has six subnetworks and 45 fiber-optic outlets for connection to user PCs, workstations, and other equipment.

These 45 nodes are distributed among six star couplers dedicated to the third floor, providing additional capacity for future expansion.

The server in the third-floor communications closet routes traffic around the subnetwork, using Novell network managemnet software.

Graduate students working under Denton's supervision are experimenting with software that will bridge between the individual subnetworks to spread traffic loads.

Other graduate students are evaluating wavelength division multiplexers for incorporation within the system.

The subnetworks on a particular floor are connected to a main floor node that is responsible for managing data between subnetworks on a floor.

Active repeaters regenerate the optical signals for distribution between subnetworks and to other floors.

A building-wide master communications node managers data flow between the main floor nodes.

It serves as a central communication point for inter-floor communications, and as a data gateway to the external campus network.

The network transceivers' output power and receiver sensitivity determine the optical power available in the subnetworks. Maximum connector loss in a subnetwork totals 1.8dB.
COPYRIGHT 1990 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Publication:Communications News
Date:Dec 1, 1990
Previous Article:And then there was light.
Next Article:DuPont data can take a hit.

Related Articles
Utility's switch adds agents within seconds.
Viva Las Vegas!!!
Organic Gobo. (Currents).
Buyers guide.
Merrill Lynch report notes concern on beer industry performance.

Terms of use | Copyright © 2016 Farlex, Inc. | Feedback | For webmasters