 system is usually integrated inside one shelf. For larger router/switch designs where mul- tiple shelves are involved, the intersystem communication is handled by optical fiber interconnect. In terms of implementation, we will present snapshots of reality through various vendor case studies in several chapters in which we cover representative products for each category. SUMMARY In this chapter, we continued looking at fundamental concepts. We first defined the multiple contexts of network realms from CPE to the WAN core. We clarified the different design requirements that drive the network equipment manufacturers' thought processes in each network context. We briefly discussed the most important operations that need to happen in real time and at wire speed inside switching/routing gear that is designed to handle packets. We also introduced many of the fundamental concepts, which we will review in depth in the subsequent chapters that discuss the techniques and typical products that implement them. 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. PACKET PROCESSING 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. Source: NETWORK PROCESSORS NETWORK PROCESSOR ARCHITECTURES 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. NETWORK PROCESSOR ARCHITECTURES 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. Source: NETWORK PROCESSORS CHAPTE