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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)

Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP) 1 IP Overview and Key Operational Characteristics

IP is a very important protocol in internetworking; it wouldn't be an exaggeration to say that you can't really comprehend modern networking without a good understanding of IP. Unfortunately, IP can be somewhat difficult to understand. This is probably because due to its importance, a large amount of complexity has become associated with the protocol over the years, to allow it to meet the many demands placed upon it.

Before diving into the details of how IP works, I feel it is worthwhile to take a high-level look at IP and what it does. In this section I provide a brief examination of basic concepts related to the Internet Protocol and how it works. I begin with an overview of IP, how it operates in basic terms and the most important characteristics of how it does its job. I then expand on this discussion by describing the main functions of the Internet Protocol, which can be used as an introduction to the remainder of the sections that explain IP in considerably more detail. I conclude with a brief look at the history of development of IP, its versions, and how it has spawned the development of several IP-related protocols.

Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP) 1 IP Overview and Key Operational Characteristics