Internet Core Protocols: The Definitive Guide

Chapter 2. The Internet Protocol

Summary	The Internet Protocol provides a basic delivery service for transport protocols such as TCP and UDP. IP is responsible for getting data to its destination host and network. IP is not reliable, so the effort may fail.
Relevant STDs	2 (http://www.iana.org/); 3 (includes RFCs 1122 and 1123); 4 (RFC 1812, republished); 5 (includes RFCs 791, 792, 919, 922, 950, and 1112)
Relevant RFCs	781 (Timestamp Option); 791 (Internet Protocol); 815 (Fragmentation Reassembly); 919 (IP Broadcasts); 922 (Broadcasting on Sub-Nets); 950 (Sub-Net Recommendations); 1108 (Security Option); 1112 (IP Multicasting and IGMP v1); 1122 (Host Network Requirements); 1349 (Type-of-Service Flags); 1455 (Data-Link Security TOS Flags); 1812 (Router Requirements); 2113 (Router Alert Option)

As we learned in Chapter 1, a variety of protocols are used for moving application data between different systems. We saw that hardware-specific protocols are used by devices when they need to exchange data directly, that the Internet Protocol is used to get IP datagrams across the different network segments to their final destination, and that TCP and UDP provide transport and connection management services to the application protocols used by end-user applications.

Although each of these layers provides unique and valuable services, the Internet Protocol is perhaps the most important to the overall operation of the Internet in general, since it is responsible for getting data from one host to ...