tailieunhanh - Internetworking with TCP/IP- P8

Internetworking with TCP/IP- P8: TCP/IP has accommodated change well. The basic technology has survived nearly two decades of exponential growth and the associated increases in traffic. The protocols have worked over new high-speed network technologies, and the design has handled applications that could not be imagined in the original design. Of course, the entire protocol suite has not remained static. New protocols have been deployed, and new techniques have been developed to adapt existing protocols to new network technologies | 38 Review Of Underlying Network Technologies Chap. 2 tablish a new connection. Furthermore identifiers used for a connection can be recycled once a disconnection occurs the switch can reuse the connection identifier for a new connection. WAN Technologies ARPANET We will see that wide area networks have important consequences for internet addressing and routing. The technologies discussed in the remainder of this chapter were selected because they figure prominently in both the history of the Internet and later examples in the text. One of the oldest wide area technologies the ARPANET was funded by ARPA the Advanced Research Projects Agency. ARPA awarded a contract for the development of the ARPANET to Bolt Beranek and Newman of Cambridge MA in the fall of 1968. By September 1969 the first pieces of the ARPANET were in place. The ARPANET served as a testbed for much of the research in packet-switching. In addition to its use for network research researchers in several universities military bases and government labs regularly used the ARPANET to exchange files and electronic mail and to provide remote login among their sites. In 1975 control of the network was transferred from ARPA to the . Defense Communications Agency DCA . The DCA made the ARPANET part of the Defense Data Network DDN a program that provides multiple networks as part of a world-wide communication system for the Department of Defense. In 1983 the Department of Defense partitioned the ARPANET into two connected networks leaving the ARPANET for experimental research and forming the MILNET for military use. MILNET was restricted to unclassified data because it was not considered secure. Although under normal circumstances both ARPANET and MILNET agreed to pass traffic to each other controls were established that allowed them to be disconnected . Because the ARPANET and MILNET used the same hardware technology our description of the technical details apply to both. In fact the technology was also