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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

TCP/IP Internet Layer (OSI Network Layer) Protocols 1 Internet Protocol Concepts and Overview

The idea of singling out any one protocol as being more important than the others in a network is kind of pointless, if you think about it. The protocols and technologies work as a team to accomplish the goal of communication across the network. Like any team, no single member can get the job done alone, no matter how good they are. Still, if we were to try to pick a “most valuable player” in the world of networking, a good case could be made that we have it here in this section: the TCP/IP Internet Protocol (IP).

Even though it gets “second billing” in the name of the TCP/IP protocol suite, IP is in fact the “workhorse” of TCP/IP. It implements key network-layer functions including addressing, datagram handling and routing, and is the foundation upon which other TCP/IP protocols are built. Even the ones lower in the TCP/IP architecture such as ARP and PPP are easier to understand when you know how IP works. In addition to the main functions implemented by the IP protocol itself, there are also several protocols that have been developed over the years that I call “IP-Related” because they are based on IP but add new functionality or capabilities for special purposes.

In this section I provide considerable coverage of the TCP/IP Internet Protocol and to several protocols that are closely related to IP. I begin with a section that takes a general look at IP concepts and provides an overview of how IP works. I then have a large section that looks at IP version 4, the current version of the protocol that is in use on TCP/IP networks everywhere. Following this I look at the “next generation” of IP, IP version 6. I then provide sections covering three IP-related protocols: the IP Network Address Translation protocol (IP NAT), the IP Security protocol set (IPSec), and the adaptation of IP for mobile devices (Mobile IP).

TCP/IP Internet Layer (OSI Network Layer) Protocols 1 Internet Protocol Concepts and Overview