Strong MAN handles Tulsa's data traffic

Strong MAN handles Tulsa's data traffic

City piggybacks its network onto cable TV services provider and saves big

By Trudy Walsh

GCN Staff

For a century, the fortunes of Tulsa, Okla., rose and fell with its boom-or-bust economy based on oil and agriculture. But city officials have found that with an asynchronous transfer mode network, Tulsa can tap into a resource that won't run dry'information.

In 1990, Tulsa's network consisted of six PCs linked to a mainframe from Bull HN Information Systems Inc. of Billerica, Mass. But the city's data communications needs grew, and the network couldn't handle the traffic. City officials knew they had to beef up the network, said Clayton Lewis, manager of Tulsa's Network Services Division.


By upgrading the city's network to ATM instead of T1 lines, Tulsa officials estimate the city saves about $10,000 each month.


In 1992, TCI, a local cable TV provider later bought by AT&T Cable Services of Englewood, Colo., asked to install fiber-optic cable throughout the area so it could offer more channels.

The city agreed to let TCI install the network if the city could use it too, paying only incremental costs. That saved a huge amount of money, Lewis said. The city hooked its network into the company's fiber-optic network while TCI laid fiber, Lewis said.

Now the metropolitan area network has been upgraded to ATM, Lewis said, and the basic horizontal network the city's 200,000 users access is 100-Mbps Ethernet.

Video, images too

The great thing about ATM is that it can handle a lot more than just data, Lewis said. For example, the Tulsa Fire Department has asked to use the MAN to conduct video training. The Police Department plans to store digital mug shots on its database in Joint Photographic Experts Group format. That wouldn't be possible with a less robust network, Lewis said.

The core of the Tulsa network runs at 155 Mbps. 'If we need more power, we can upgrade it,' Lewis said. 'That's the beauty of a fiber infrastructure.'

Most of the network's switches and routers are from 3Com Corp. of Santa Clara, Calif., and its firewalls are from Cisco Systems Inc. of San Jose, Calif., Lewis said.

Despite the influx of new systems into the city in the mid-1990s, some city departments kept their legacy systems. Tulsa network managers use 3Com NetBuilder II routers to connect legacy Fiber Distributed Data Interface connections to the main MAN. Sixteen 3Com CoreBuilder 7000 ATM switches provide OC-3 links to a SuperStack II Switch 2700/ATM Ethernet switch in each of the city government's 130 buildings.

Two CoreBuilder switches link to the police and court system database. The city is also installing a SuperStack II 3300 switch at 13 Tulsa county libraries that link at the 155-Mbps OC-3 rate to a backbone CoreBuilder 7000 switch.

The library portion of the MAN runs on a virtual LAN within the ATM network, Lewis said. 'That way we don't run the risk of having some high school genius hacking into the system. It's a separate, secure system.'

Lewis estimates that by running the city's MAN on ATM, instead of T1 lines or the slower speeds provided by phone company data links, Tulsa saves about $10,000 a month. That's how much it would cost the city to lease enough T1 lines to perform the services ATM performs, he said.

'We could never afford to lease services to 200,000 users in 150 locations,' Lewis said. 'There's just no comparison.'

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