inated the M13 process entirely? What if we could do it as simply as the process shown in Figure 3-50? We have. It's called SONET in North America, SDH in the rest of the world, and it dramatically simplifies the world of high-speed transport. SONET brings with it a subset of advantages that makes it stand above competitive technologies. These include mid-span meet, improved OAM&P, support for multipoint circuit configurations, unintrusive facil- ity monitoring, and the ability to deploy a variety of new services. We will examine each of these in turn. SONET Advantages: Mid-Span Because of the monopoly nature of early networks, interoperability was a laughable dream. Following the divestiture of AT&T, however, and the realization of Equal Access, the need for interoperability standards became a matter of some priority. Driven largely by MCI, the newly Figure 3-50 SONET ADM A much simplified add- drop process! Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Telephony Chapter 3 competitive telecommunications industry fought hard for standards that would allow different vendors' optical multiplexing equipment to inter- operate. This interoperability came to be known as "mid-span meet," SONET's greatest contribution to the evolving industry. Improved OAM&P Improved OAM&P is without question one of the most important contri- butions that SONET brings to the networking table. Element and Net- work monitoring, management and maintenance have always been something of a catch-as-catch-can effort because of the complexity and diversity of elements in a typical service provider's network. SONET overhead includes error-checking capability, bytes for network surviv- ability, and a diverse set of clearly defined management messages. Multipoint Circuit Support When SONET was first deployed in the network, the bulk of the traffic it carried derived from poi