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Tymnet and Tymnet again: Everything old is new again as MCI upgrades its legacy network for the next century

Incumbent carriers in all segments of telecommunications have many obvious advantages over the new breed of carriers that are seeking to dethrone them. However, while those new carriers face the challenges and risks of building new networks, incumbent carriers face an equally difficult and complex agenda. They must assess the long-term value of their legacy network architectures, elements and services, re-engineering them in a cost-effective but progressive way-or relegating them to the trash heap when necessary.

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If re-engineering is the chosen path, that likely will mean broad upgrades for carrier central offices and other switching centers to convert them from legacy outposts to modern hubs in a progressive network fabric.

Standing the test of time Heading into the mid-1990s, MCI's Tymnet network was clearly a network of an older era. In fact, it is older than the company that currently owns it. Tymnet was originally built in 1966 as Tymshare, a network devoted to the fast-growing access needs of corporate users.

"These companies had difficulty getting the access lines that they wanted, so they built their own network," says Dennis Jonas, advisory engineer for local and strategic engineering in MCI's chief technology office. By the time Jonas joined Tymshare in 1979, it was a 300-node network.

With private networking starting to boom in the early 1980s, McDonald Douglas, one of Tymshare's owners, acquired the entire business and network in 1983. Six years later, the network came into carrier hands for the first time, when BT bought Tymshare and changed its name to Tymnet. Ownership recently changed again when BT initiated its merger with MCI, which involved selling its North America holdings to MCI.

Although BT is fully out of the picture now, and MCI is being acquired by WorldCom, Tymnet has so far survived its transient past to remain a strategically valuable network. It now has about 5200 nodes, 4000 of which are in the U.S. However, as the network turned 30 years old, a major upgrade was necessary if Tymnet was going to continue as a cost-effective backbone.

"We had far too much equipment for what we were doing, equipment that was far too old," says Jonas. "The network was living in the '70s."

Upgrade in progress Jonas planned the networkwide upgrade, which began in 1996 and is still ongoing. The project aimed to reduce operating costs for Tymnet's 115 legacy X.25 switching centers, while migrating away from a technical and cumbersome assembly language operating system that Tymnet had developed. The company wanted to replace proprietary equipment and protocol with open, modern off-the-shelf solutions that could improve the efficiency of these centers.

MCI was seeking to install about one new system for every five to 10 pieces of legacy server equipment housed in its switching centers, says engineer Jonas.

MCI also wanted to reduce the number of access nodes in the network by closing more than 400 asynchronous access sites and back-hauling the access points to other nodes. "Our eventual goal is to collapse more than 500 access nodes into about 50," says Jonas.

While these challenges are significant, the process of conducting such upgrades is often the most difficult task. With competition closing in, carriers such as MCI depend heavily on their glowing reputations for service reliability, but network equipment upgrades can sometimes require a service disruption, particularly when they involve older equipment.

"In the past, I/O cables were connected directly to customer premises units, so it took a superhuman engineering feat to get a new system up and running," says Jonas, adding that it was imperative not to disrupt service during the Tymnet upgrade.

Jonas decided that the Solaris operating system developed by Sun Microsystems fit the bill for Tymnet's operations and management needs. Although rack-mount solutions tend to cost more than other options, the ease and speed of installing rack-mount systems promised to minimize the time and hassle inherent to a broad network upgrade.

MCI contracted with Sun reseller Artecon to carry out the upgrade. Artecon's rack-mount PowerSphinx solution, based on Sun's Sparc 20, supports a -48 volt DC power environment for standard 110-volt servers and peripherals, and it is compliant with Bellcore NEBS.

MCI installed 25 Sphinx units in switching centers in Dallas and Chicago during the second half of 1996 and so far has installed about 120 units in these and other cities, including Los Angeles, San Jose, Doraville, Ga., and Fairfax, Va.

Upgrades that previously took days are now taking only a few minutes because rack-resident equipment can be easily moved in and out of rack-mount designs. In Artecon's solution, the racks offer unobstructed backplane access, while the workstations stay in their original casing. These facts also bode well for the future because MCI will be able to conduct quick, smooth upgrades whenever Sun offers new Sparc versions.

"MCI was concerned about how long an upgrade like this could take," says Mike Seidel, business development manager at Artecon. "Telcos can be incredibly fussy about how their COs are put together, but they have to be because they have reputations for reliability on the line."

Minimizing labor time is not the Sphinx rack's only benefit. The rack is designed only slightly larger than the Sparc 20 itself, so that the server footprint is kept to a minimum.

"There is concern in the industry about upgrading from legacy equipment to modern equipment," says Seidel. "Because of this, telcos generally don't modernize until their hand is forced."

That is especially true of the last few years. Many telcos hoping to establish more efficient operations have launched projects to re-engineer their COs only to find that the execution of these projects is impractically slow or complex. However, competition is a forceful hand if ever the industry has seen one, and modernizing the network every 30 years will no longer suffice. Rack-mount frameworks may be a quick, methodical solution for bringing networks into the '90s and beyond.

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© 2014 Penton Media Inc.

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