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TCP/IP Protocols Overview

DARPA: The Defense Advanced Research Project Agency

The United States Department of Defense began building a network in 1968 through its Advanced Research Projects Agency (ARPA). This network, called the ARPANET, was designed to meet a specific set of goals:

• Share large-scale (..in 1968?) computer resources
• Develop a reliable digital communications infrastructure

By 1975 the network consisted of only about 60 nodes and was, at that time, expanding at the rate of about one node every three months. The ARPANET grew, expanded, and the rest of the computing community joined in and, today, we have The Internet. The growth rate of the Internet has been exponential and the exact number of nodes is unknown. It's probably in the hundreds of millions.

Originally, a Network Control Center was established through the company Bolt, Beranek, and Newman along with an additional Network Control Center at the Stanford Research Institute in Palo Alto, California. They used a DEC PDP-10 computer as the single, central controller for the ARPANET.

A family of communications protocols was developed to meet the objectives of the ARPANET. The original objectives continue to be met by these protocols, now known as the TCP/IP, or simply, the IP Protocols. These objectives included the following (Compendium topics are linked):

• Internet Protocol (IP)
  An addressing scheme to logically identify devices and to group them into networks
• Address Resolution Protocol (ARP)
  The ability to resolve physical addresses when a logical (IP) address is known
• Domain Name Service (DNS)
  A redundant storage system for network address information
• Routing Information Protocol (RIP)
  The ability to re-route to an alternative path if a current path becomes unusable through router configuration
• Internet Control Message Protocol (ICMP)
  The notification of error conditions on the network
• User Datagram Protocol (UDP)
  A simple mechanism for exchanging data messages
• Transmission Control Protocol (TCP)
  The reliable transfer of data as required
• File Transfer Protocol (FTP)
  Trivial File Transfer Protocol (TFTP)
  The ability to transfer files
• Simple Main Transfer Protocol (SMTP)
  A mail messaging system
• Telnet
  The ability to act as a terminal to a host computer

And, as the years went by, more additions were made to the original protocols, enhancing and expanding the original functionality. Here is a broad outline of some of these newer capabilities:

• Open Shortest Path First (OSPF)
  Cisco's Internet Gateway Routing Protocol (IGRP)
  Enhanced Internet Gateway Routing Protocol (EIGRP)
  Enhanced routing capabilities
• Network Information Service (NIS)
  Expanded capabilities for storing network information other than addresses
• Simple Network Management Protocol (SNMP)
  Remote router management
• Network File System protocol (NFS)
  The ability to mount a remote file volume and treat it as if it were local
• Remote Procedure Call protocol (RPC)
  A programming interface to facilitate the programming of network services
• Boot Protocol (BOOTP)
  Dynamic Host Configuration Protocol (DHCP)
  Enhanced capabilities to provide bootstrap information for network clients
• The Remote Monitoring MIB (RMON)
  The acquisition of network performance data

This section of the compendium discusses the broad spectrum of protocols under the umbrella of Internet Protocol. It is, by no means, complete - but we're working on it. Refer to the NEWS section to find out what the most recent changes are to the Compendium.

Topics In This Discussion

• Internet Protocol (IP)
• Address Resolution Protocol (ARP)
• Internet Control Message Protocol (ICMP)