 processors are needed. In this introduction, we have seen how and why the sheer quantity of network-related data processing has rapidly evolved to unprecedented levels of sophistication and complexity from many angles. Today's network equipment must be able to parse packets, search lookup tables that document poli- cies, resolve conflicting operations that seem necessary, potentially modify the packet's content by adding or removing bits, possibly encrypt payload and authenticate the other party, generate digital signatures and verify other parties' signatures, create secure tunnels (for example, IPsec stipulates building the so-called Authentication Header [AH] and Encapsulating Security Payload [ESP] head- ers), encapsulate traffic into tunnels, and engage to modular arithmetic (indispensable for encryption operations) and, more specifically, to modular multiplication and exponentiation. The list of tasks for the hardware inside network equipment can go on and on. Ordinary CPUs sim- ply cannot handle these tasks for many reasons, including software complexity, system throughput, and operations latency. Special hardware based on optimized architectures is needed together with the availability of cutting-edge development tools, which will help shrink the time-to-market nightmare that companies confront. In short, new types of advanced microchips are required for the timely and efficient handling of these requirements. These are called network processors, which are the subject of our study in the rest of this book. SUMMARY In this chapter, we provided a very short historical and qualitative overview of the evolution of com- puting and networking communications technologies over the last 30 years. This evolution has largely 67. Y. Berner et al. "A Framework for Differentiated Services," draft-ietf-difserv-framework-02-.txt, February 1999. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject 