SONET and SDH are U.S. and international standards, respectively, for optical telecommunication transport. The SONET/SDH comprehensive standards will continue to define the world's telecommunication transport infrastructure for the foreseeable future.

As the standard for network transport, protocol, and architecture, SONET/SDH has eliminated the different transmission schemes and rates of North America, Europe, and the Pacific Rim through a common international rate structure. It also provides a technology that enables the major service providers to internationally standardize and control broadband network transport media through a common fiber interface called a mid-span meet.

Probably the greatest benefits of SONET/SDH lie in its in-band OAM&P. SONET/SDH systems provide increased configuration flexibility and bandwidth availability over older telecommunication systems, thus providing major advantages, such as

• Reduction of equipment needed and increased network reliability and availability
• Centralized fault isolation and management of payload (traffic carried)
• Synchronous multiplexing formats for DS1 and E1 allowing easy access for switching and multiplexing
• International vendor interoperability
• Flexible architecture able to accommodate future requirements
• Increased Bandwidth
• Increases in the network reliability