o ensure the dynamic adaptation of the network to changing traffic patterns and loads. For instance, under these premises, the following would be required: The capability of fast rerouting. The possibility of calculating alternative routes. The facility of presignaling these new backup-plan routes, SO that they can transparently pick up the workload from operating tunnels that are suddenly less efficient. These capabilities directly increase the resilience and survivability of the network, while they indi- rectly improve its scalability. Currently, MPLS networks provide very powerful TE capabilities. This adds to the functionality and performance requirements of the router circuitry. Customers are no longer interested in signing up with carriers or service providers for a number of communications channels at some aggregate data bit rate. Several applications that are tightly related with the customer's organizational needs require different levels of service, response time, bandwidth, delay, jitter, cost, and SO on. Customers are not willing to pay the same rate for all their needs. New business models have been developed that bill the customers based on what they actually use and what the content is. Service providers must now be able to treat different services that they provide with different cri- teria, which must be made to apply optimally to the customer's diverse requirements. In other words, not all bits are to be treated in the same way. Several new protocols appear from various standardiza- tion bodies, such as Differentiated Services (DiffServ), Integrated Services (IntServ), and RSVP. 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 28 NETWORK PROCESSORS Previously, frame relay and ATM treated issues of QoS at layer 2, whereas protocols such