EE 228 a - Lecture 2 - Spring 2006 Internet

In today’s class, we cover the topic of the Internet with emphasis on review of TCP/IP. ( A good reference is [1] and a slightly more readable but less comprehensive is [2] I. NETWORKS Communication networks are usually defined by their size and complexity. From top-down, we have • Wide area networks(WAN) These networks connect computers and other terminals over large distances. They often require multiple communication connections, including microwave radio links and satellite. WAN consists of the back-bone networks that are connected via high capacity fiber optics cables. • Metropolitan area networks(MAN) These networks are interconnected within a WAN and are spread around , say, a town or city. This kind of network is a high speed network using optical fiber connections. • Local area networks(LAN) These networks are components of a MAN to connect computer and other terminals distributed in a localized area. The connection is usually cable (twisted pair copper) or fiber. Figure 1 shows the possible components of a LAN Fig. 1. The possible components of a LAN II. HISTORY Table I lists the milestones in the development of the Internet. TABLE I MILESTONES IN DEVELOPMENT OF INTERNET 1962 L. Kleinrock proposes Packet Switching 1966 L. Roberts proposes architecture to Darpa 1969 First demonstration of packet switching: 4-node Arpanet 1969 S. Croker introduces RFCs (managed by J. Postel) 1972 R. Kahn proposes an open architecture: Inter-networking with stateless routers, best effort, no control plane 1973 Kahn and V. Cerf propose early ideas of IP (32-bit address) and TCP (end-to-end ACKs with a window scheme) 1973 R. Metcalfe invents Ethernet 1982 IGP and EGP Late 1970s, early 1980s Berkeley develops BSD, a modified implementation of UNIX that includes TCP/IP 1983 Arpanet switches to TCP/IP 1983 P. Mockapetris invents DNS 1988 Van Jacobson fixes TCP 1985 1995 Internet supported by NSF and other agencies 1993? T. Berners-Lee invents WWW 1995 Internet is privatized 2000 WiFi,VoIP, P2P