dent upon the layers surrounding it. The Application Layer, at the top of the model, "speaks" to the actual application process that creates the information to be transported by the 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. Protocols Chapter 2 Figure 2-11 OSI Model Application Presentation Session Transport Network Data Link Physical network; it is closest to the customer and the customer's processes, and is therefore the most customizable and manipulable of all the layers. It is highly open to interpretation. On the other end of the spectrum, the Physical Layer dwells within the confines of the actual network, and is totally standards dependent. There is minimal room here for interpre- tation; a pulse is either a one or a zero-there's nothing in between. 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. Protocols Protocols Figure 2-12 Chained VS. end-to-end layers Application Presentation End-to-End Layers Session Transport Network Chained Layers Data Link Physical Physical Layer standards, therefore, tend to be highly commoditized, while Application Layer standards tend to be highly specialized. This becomes extremely important as the service provider model shifts from delivering commodity bandwidth to providing customized services-even if they're mass customized- to their customer base. Service providers are clawing their way up the OSI food chain to get as close to the Application Layer end of the model as they can because of the Willie Sutton Rule. 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 we