Bethlehem Steel uses intelligent T1 ESF CSUs to build strong network.

Bethlehem Steel Corporation was founded in 1857 as Saucona Iron Co. whose primary product was railroad rails. Today it is the second largest integrated steel producer in the United States, shipping 8,865,000 tons of steel in 1990 for automobiles, appliances, machinery, construction, and other uses.

Bethlehem Steel Data Communications Services uses dedicated T1 circuits between corporate headquarters, steel plants and research facilities for nearly all data communications needs including order processing, process control information, research, quality control, inventory, and administration.

When it was installed in 1986, the T1 backbone was a triangle topology with links between the corporate headquarters data center in Bethlehem, Pa., and the steel plants in Steelton, Pa. and Sparrows Point, Md. Bethlehem Steel also installed a dedicated T1 from the data center to the research labs also located in Bethlehem.

At this time the other mills in Burns Harbor, Ind.; Lackawanna, N.Y.; and Johnstown, Pa., were not part of this network.

In 1989, a decision was made to upgrade the equipment on the network and expand it to include these sites because of the cost savings that could be realized.

This change provided us an opportunity to address one of the more serious problems on the network: T1 line failures and degradation.

The network was experiencing a considerable amount of unscheduled downtime due to the "dumb" CSUs that were originally installed. With T1 circuits, there is usually a gradual degradation before the circuit fails entirely. The data communications technicians had no way of tracking and recording error rates or lost signals; these CSUs could not provide this information.

The ability to track degradation trends was necessary to anticipate potential failures, then schedule downtime to perform intrusive testing on the circuit to fix the problem.

The line failure problems were compounded by the test procedures required.

When a line problem was indicated, the technicians would have to disconnect the multiplexer to connect the test equipment, taking the circuit out of service. Once the tests were completed, the trouble was reported to the carrier. At times these outages would last for hours.

Realizing that increasing the number of our backbone links while still using the dumb CSU equipment, the number of line problems and the manpower requirements for circuit maintenance would increase proportionately, which was an unaccetable situation.

Network expansion

The plans to expand the backbone gave Bethlehem Steel the opportunity to evaluate and install non-intrusive, intelligent, line monitoring equipment. Data Communications decided to add the ESF (Extended Superframe) facility data link option to the T1 service, upgrade the multiplexers, and replace the CSU equipment.

By doing so, Bethlehem Steel could take advantage of the ESF option, giving us the ability to perform non-intrusive testing.

Data Communications evaluated CSU equipment from what we considered the top three vendors. The T-Smart Intelligent CSU from ADC Kentrox was selected because, at the time of our evaluation, it offered features and advantages over the competition.

First, it includes three sets of registers: network interface, terminal interface, and carrier registers.

The addition of the terminal interface registers means that if is there is a great distance between the CSU and the multiplexer, T-Smart allows Data Communications to monitor this portion of the circuit. The ability to monitor at the network and the terminal interfaces gives Data Communications monitoring capability for the entire facility.

Another advantage is the additional set of loopback commands. This is effective when there are applications requiring two T1 circuits to be tied together, resulting in a configuration that is essentially four CSUs on one facility.

By optioning the CSUs to respond to one set of loopback commands and ignore the second set of commands, single-ended fault isolation can be performed.

These features give Data Communications the ability to distinguish terminal equipment problems from network problems without taking the circuit down.

Data Communications replaced the dumb CSUs and installed a total of 18 T-Smarts throughout Bethlehem Steel's network. They are monitored in the Data Communications center through MultiSmart Supervisor, also from ADC Kentrox.

MultiSmart Supervisor is a PC-based system that automatically polls each T-Smart routinely to check for errors and monitor line performance. This way, Data Communications can detect degradation trends and make the appropriate changes before problems occur.

At all our locations, Data Communications has installed T-Smart shelves with attached modems. MultiSmart Supervisor allowed us to set up batch-like programs to automatically dial out each morning to every T-Smart, query the registers and pull the error information back to a file on disk located in the Data Communications center.

Equipment in mothballs

Since the new equipment was installed, Data Communications technicians have not had to connect a single test set to any of the T1 circuits. This eliminated the need for end-to-end testing, which previously required personnel at both ends of the circuits.

Now we know, by remote query of T-Smart's registers, when errors occur. Through MultiSmart Supervisor, we select the location where the problem is indicated, dial into the CSU and check the registers.

Ron Carter, Sr. Operations Analyst Bethlehem Steel Corp.