SONET Offerings for Enterprises

Local telephone companies sell SONET (Synchronous Optical Networking) transport for connections between local customers and interexchange carriers. The speeds offered are at OC-3 (155 megabit), OC-12 (622 megabit), and OC-48 (2.5 gigabit) rates. The local telephone companies guarantee 50 millisecond network restoration in the case of a network failure or degradation. They run the SONET service to multiple local central offices. In the case of a failure at one CO (Central Office), service is immediately available from the backup CO. Matching SONET multiplexers are required at the customer premises and at the telephone company office. Another variation of SONET service protects customers from fiber cuts. This diverse routing scheme offers fiber from separate building entrances to the same CO.

Customers often opt for point-to-point SONET rather than bidirectional rings to save money. The major impediment on sales of these services is the cost to dig trenches for additional fiber runs from the customer to the incumbent carrier's fiber ring. Because it is lower in price, newer Ethernet services at gigabit or lower speeds ranging from 10 megabits to 500 megabits are gaining in popularity for data communications. However, customers with existing SONET service have the option to add Ethernet data that runs at 10, 50 or 100 megabits per second. This uses spare capacity on the SONET multiplexer for perhaps LAN-to-LAN connections in metro areas.