protocols over ATM, Multiprotocol Over Asynchronous Transfer Mode (MPOA). In retrospect, it is rather easy to state that ATM has failed to become the astounding success it had originally promised for a couple of reasons. The most important reasons are as follows: The establishment of IP running over ATM as the predominant realm, within which routing deci- sions were being taken by network equipment operating at a higher layer than where ATM was, left no room or need for an intelligent ATM switch under it. The bandwidth and QoS services that ATM was designed to offer in the WAN were going to be offered by the newer layer 3 switching techniques (such as Multiprotocol Label Switching [MPLS], which we will discuss in another section). At the campus level, other technologies appeared such as Gigabit Ethernet, which was not only faster than ATM's 622 Mbps transfer rate, but it was also completely compatible with legacy Ethernet applications and software written for 10Base-T era networks. ATM was left in a perpetu- ally hopeful mood, only now without any real prospects. 24. David E. McDysan and Darren L. Spohn, ATM Theory and Applications (New York: McGraw-Hill, 1998). 25. Mohsen Gluzani and Ammars Rays, Designing ATM Switching Networks (New York: McGraw-Hill, 1999). 26. David McDysan, QoS and Traffic Management in IP and ATM Networks (New York: McGraw-Hill, 1999). 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. THE EVOLUTION OF NETWORK TECHNOLOGY: DISTRIBUTED COMPUTING AND THE CONVERGENCE OF NETWORKS 16 NETWORK PROCESSORS Today ATM is mostly confined in the backbone of some long-distance or metro carriers. As a result, it must be utilized for the efficient and billable transfer of pertinent layer 3 protocols such as IP. The IETF quickly established how IP should be transferred over an ATM network. It is one of the current techniques used for the t