cted devices time to recover before the onslaught begins anew. The problem with FECN and BECN lies in the fact that many devices choose not to implement them. They do not necessarily have the inherent ability to throttle back upon receipt of a congestion indicator, although devices that can are becoming more common. Nevertheless, proprietary solutions are in widespread use and will continue to be for some time to come. 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. Transport Technologies Transport Technologies Frame Relay Summary Frame relay is clearly a Cinderella technology, evolving quickly from a data-only transport scheme to a multiservice technology with diverse capabilities. For data and some voice and video applications, it shines as a WAN offering. In some areas, however, frame relay is lacking. Its band- width is limited to DS3, and its ability to offer standards-based QoS is limited. Given the focus on QoS that is so much a part of customers' mantra today, and the flexibility that a switched-solution permits, some- thing else was required. That something was ATM. Asynchronous Transfer Mode (ATM) Network architectures often develop in concert with the corporate struc- tures that they serve. Companies with centralized management author- ities such as utilities, banks, and hospitals often have centralized and tightly controlled hierarchical data-processing architectures to protect their data. On the other hand, organizations that are distributed in nature-such as research and development facilities and universities- often have highly distributed data processing architectures. They tend to share information on a peer-to-peer basis and their corporate structures reflect this fact. ATM came about not only because of the proliferation of diverse net- work architectures but also because of the evolution of traffic character- istics and t