Coast Guard adds Fast Ethernet connections to ship, shore LANs

The Coast Guard has launched a $52 million project to upgrade LAN infrastructures
aboard more than 300 ships and at more than 400 shore sites over the next year.


The Workstation 3 LAN Cabling Project will bring switched Ethernet to the desktops of
Coast Guard users via a Fast Ethernet fiber backbone.


“Right now, we’re optimistic” that a September 1999 deadline will be
met, said Cmdr. Ken Savoie, engineering chief at the Coast Guard’s Information
Systems Directorate.


The networks are being built around 1,300 SuperStack II switches from 3Com Corp. of
Santa Clara, Calif. Each switch is gigabit-ready on the backplane, providing a future
migration path to Gigabit Ethernet, if needed.


The Coast Guard’s older shared Ethernet environment had been straining to support
shore- and ship-based applications, Savoie said. The new 3Com switches are stackable for
high port density in a small footprint—important aboard ships.


SuperStack II 3300 switches on the backbone will make 100-Mbps Fast Ethernet
connections to servers and to SuperStack II 1100 switches at the edge of each LAN. The
1100s will deliver 10- or 100-Mbps desktop connections over Category 5 unshielded
twisted-pair copper cabling.


Shipboard LANs will have all-fiber cabling, which is more robust and less vulnerable to
interference in a crowded shipboard environment, Savoie said. In case of fire, the fiber
cable will give off little smoke and no halogens.


Most Coast Guard bases have several detached buildings with limited numbers of users.
These users will connect to the LANs at distances of up to 1,500 feet via Ethernet
repeaters. Users at distances of up to 12,000 feet will get high-bit-rate digital
subscriber lines, or HDSL.


HDSL can supply 1.54-Mbps connections, over a four-wire loop of two pairs, up to 12,000
feet, if no more than six desktop users are involved. Sites with more than six users or
longer distances will require additional fiber.


“HDSL saved us a lot of money, because we didn’t have to pull as much fiber
conduit,” Savoie said. HDSL connections also will link the shipboard LANs to
land-based networks when Coast Guard vessels dock. 

About the Author

William Jackson is a Maryland-based freelance writer.

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