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An upgrade to the campus data network is now 75 percent complete, bringing
improved performance and a foundation for new services to the Dartmouth
community.
Since the fall term, Network Services has been installing new network
devices in buildings throughout the campus and deploying a new fiber-optic
"core" network that rings the campus.
During spring break, technicians connected three-quarters of campus
buildings to the new core. The remaining buildings will be cut over in coming
weeks, with the entire project scheduled for completion in June.
The biggest benefit for most people will be faster file transfers. Most
computers share a connection to the core network with up to 10 other people
through a device called a hub. The shared line is usually fast enough for most
purposes, until other people start to use it. When that happens, traffic slows
down.
The hubs in each building have been replaced with switches, which eliminate
the shared-line bottleneck. In addition, the switch can detect how fast your
computer can talk on the network, and adjust accordingly. If you have a 10/100
Ethernet card, the switch will know it can communicate at the higher speed.
The core network itself will also run much faster with the new electronics
and fiber. The advertised speed of the circa-1995 core network now being
upgraded was 100 megabits per second, but data couldn't really travel that fast
without suffering some problems. The new core network that connects buildings
now runs at a full 1,000 mbps, or "gigabit," on
"single-mode" fiber — the same type used to carry transcontinental
telephone traffic.
The single-mode fiber was installed — but never "lit" — when the
network was last upgraded. At that time, the electronics that would support
single-mode were still in development. But planners knew it would be far less
expensive to piggyback the fibers needed for a future network upgrade while
they were already busy upgrading all sorts of other wiring — network, phone,
and Cable TV.
That speed will be apparent when transferring large files, or performing a
backup across the network. Other factors not related to the network may reduce
transfer speeds — for example, general congestion on the Internet or
Dartmouth's limits on so-called "recreational" network use.
The upgraded network will also be capable of supporting a new generation of
services, including:
- Telephone traffic over the data network — called Voice over Internet
Protocol, or VoIP. A VoIP network will bring big potential cost savings, among
other things.
- Virtual LANs. A V-LAN allows different kinds of networks — such as
Ethernet, wireless, VoIP — to share the same physical wiring, but operate as if
it were on its own wires. That makes it far easier to implement and manage new
network services.
- Virtual Private Networks, or VPNs. A huge benefit to people working from
off campus, a virtual private network allows two computers on a public network
to talk to each other directly and without fear of eavesdropping, using
encryption technology.
Network administrators are now poised to sweep away old networking gear
first installed 20 years ago — the venerable "NEDcos" — as well as
the old Macintosh gateways that service the CFS houses.
Some areas of campus have already been "swung" to the new
electronics, including the medical school and parts of the Rope Ferry complex,
with more happening each week. In all, more than 300 buildings will be upgraded
this spring.
To keep up with the project, be sure to check BlitzMail's "Computing -
Outages" Bulletin topic.
(Posted 3/27/03)
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