While copper cable remains the standard for connecting PCs to LAN hubs and switches, optical fibre may soon be the preferred way to make 10Mbps (megabits per second) and 100Mbps. Ethernet connections to corporate desktops, according to a recent study completed in July by The Tolly Group in Manasquan, N.J.
The problem in using optical fibre has been the cost, said Kevin Wilcox, assistant vice-president of technology at financial services company Fiserv Inc. in Brookfield, Wis.
But in a recent major upgrade to the LAN that connects 1,100 PCs and other devices on Fiserv’s two-building headquarters campus, Wilcox discovered that the cost to install optical fibre throughout, including horizontal runs directly to desktops and vertical cable runs to connect different floors, was about the same as using Category 5 copper Ethernet cable.
Wilcox’s installers used optical fibre and connectors from 3M Co. in St. Paul, Minn.
The Tolly Group study supports Wilcox’s experience.
Tolly Group analyst John Curtis, who completed the study in July, said choosing optical fibre over copper means you don’t have to install workgroup switches and routers on each floor of a building. Instead, networked devices in any given area are connected by optical fibre to an optical patch panel nearby. Other optical fibre runs connect these individual patch panels to a central network wiring closet in the building.
In the new optical model, Curtis said, network managers replace switches and routers with patch panels and centralize functions of the latter in a single wiring closet; there’s no need to duplicate them in several intermediate wiring closets, according to Curtis. That means less equipment to maintain and the flexibility to make more network connections in less space.
Gus Jones, director of technology information at George Washington University in Washington, said that before he revamped the university’s network, he hired an outside firm to compare the cost of using optical fibre and a centralized LAN architecture to that of installing distributed architecture over copper.
The cost of installing a copper-cabled LAN in the university’s administration building worked out to approximately US$250,000, Jones said. But using optical fibre was only US$5,000 more.
In the end, it took 11 closets to create an optically connected LAN covering 80 buildings on the George Washington campus, Jones said, compared with an estimated 160 wiring closets had he used copper.
“Initially, it was difficult to find manufacturers who would put fibre ports on their LAN switches,” Jones said. But Paris-based Alcatel finally came through with switches that were optical-ready.
Another reason Wilcox and Jones chose optical over cable was distance. The maximum distance for sending Ethernet signals over copper is about 100 meters, compared with 325 to 500 meters over fibre, said Mike Lynch, a 3M spokesman.
