The impact of fiber management: automated fault-detection tools can speed the repair of...

Traditionally, automated network management was considered a means to achieve greater internal efficiencies. Today, fiber network management is seen as a vital business strategy.

In a typical fiber-management system, or remote fiber test system (RFTS), two operational features are key:

fault detection/isolation and early detection of physical plant degradation. Fault detection/isolation represents one of the strongest features of the RFTS. In the event of a cable break, the monitoring system is able to detect the physical problem (the fault), diagnose the problem and then correlate this information with the geographical information system (GIS) documentation program to isolate the fault in less than a minute.

This information is then broadcast to a number of systems with which the RFTS integrates (e.g., alarm manager, trouble-ticketing system, direct dispatch through pager or SMS). The net result is immediate dispatch of restoration personnel to the fault location. Users of RFTS often realize a four- to six-hour decrease in repair time.

Proactive maintenance and care of network infrastructure are two of the best ways to provide peak network performance. As designed, the RFTS provides a time-stamped characterization of the network segments. In particular, the optical time domain reflectometer (OTDR) trace provides a measure of attenuation, reflectance and discontinuities along the entire length of the cable for the fibers under surveillance. This data provides a benchmark from which to continually assess network quality.

Through generation of appropriate system reports, network managers can identify and track potential hot spots. This allows for improved work crew prioritization. In situations where work crews are contracted, the reports may be transferred to the maintenance company, as well.

In the case of buried cable, the RFTS may provide the only indication of cable quality. In general, the overall effect of early detection through RFTS will be reduced operating costs through proactive network maintenance.

Other uses of RFTS include as a construction tool, where not-yet-commissioned cables are being monitored from time of deployment until initiation of traffic; as a documentation tool that holds the outside plant (and inside plant) network topology and geographic information; and as an archive of all test data for the optical cables, and, in the event of a cable break, a series of events take place that leads to final fault resolution.

In the event an organization leases bandwidth or fibers guaranteeing a certain quality of service (QoS), in must cases, the guaranteed levels of QoS can only be achieved with use of an RFTS. The RFTS will provide an early warning, preventing the cable break altogether or, when the cable break occurs, it will pinpoint the location of the cable break within minutes, making the outage shorter.

The cost of an RFTS installation can be compared with that of the alternative-portable OTDR equipment--by assuming that the cost per site is about twice that of an OTDR, that the number of RFTS sites is about the same as the number of portable OTDRs needed to maintain the network, and that the RFTS equipment will be replaced at a rate less than half as frequent as the portable OTDR equipment. Applying these assumptions results in au annual RFTS cost similar to that of using portable OTDR equipment.

As an example, 1,200 kilometers of fiber-optic cable may be monitored with an RFTS consisting of four sites. If each site monitors a total of four inactive fibers, the cost per site is approximately $30,000, including cost of" computers and software, for a total of $120,000. The same network can be maintained using a total of four portable OTDRs. With an approximate OTDR list price of $15,000 fm comparison, the cost of the OTDR equipment becomes $60,000.

For more information from NetTest: www.rsleads.com/310cn-257

Harry Mellot is the marketing communications manager, instruments group, for NetTest, Utica, N.Y.