The Illustrated Network- P6:In this chapter, you will learn about the protocol stack used on the global public Internet and how these protocols have been evolving in today’s world. We’ll review some key basic defi nitions and see the network used to illustrate all of the examples in this book, as well as the packet content, the role that hosts and routers play on the network, and how graphic user and command line interfaces (GUI and CLI, respectively) both are used to interact with devices. | CHAPTER 1 Protocols and Layers 19 feedback is required most of the feedback is provided in the drafting process . Each RFC is edited assigned a number and available to all. Not all RFCs are standards even those that define protocols. This book will make heavy use of RFCs to explain all aspects of TCP IP and the Internet so a few details are in order. RFCs have various maturity levels that they go through in their lifetimes according to their requirement levels. The RFC life-cycle maturity levels are shown in Figure . Note that the timeline does not always apply or is not applied in a uniform fashion. A specification can fall into one of six maturity levels after which it passes to historical status and is useful only for tracking a protocol s development. Following introduction as an Internet draft the specification can be a Proposed standard The specification is now well understood stable and sufficiently interesting to the Internet community. The specification is now usually tested and implemented by several groups if this has not already happened at the draft level. Draft standard After at least two successful and independent implementations the proposed standard is elevated to a draft standard. Without complications and with modifications if specific problems are uncovered draft standards normally become Internet standards. FIGURE The RFC life cycle. Many experimental RFCs never make it to the standards track. 20 PART I Networking Basics Internet standard After demonstrations of successful implementation a draft standard becomes an Internet standard. Experimental RFCs Not all drafts are intended for the standards track and a huge number are not . Work related to an experimental situation that does affect Internet operation comprise experimental RFCs. These RFCs should not be implemented as part of any functional Internet service. Informational RFCs Some RFCs contain general historical or tutorial information rather than instructions. RFCs are further .
