6 Some Hot Topics in Data Communications Email Spamming 13 billion spam emails/day, $10 billion losses this year Worm/virus attacks W32/SirCam@MM (Mass Mailer Worm) Alert Blaster worm Hacking Great Global Grid (GGG) Web services
7 Data Communications Definitions: Data Communications The movement of computer information from one point to another by means of electrical or optical transmission systems. (How about satellite system?) Such systems are often called data communications networks. Telecommunications Includes the transmission of voice and video as well as data.
8 A Brief History of Telecommunications 1837 - Samuel Morse exhibited a working telegraph system. 1843 - Alexander Bain patented a printing telegraph. 1876 - Alexander Graham Bell, invented the first telephone. 1880 - first pay telephone 1915 - first transcontinental telephone service and first transatlantic voice connections. 1947 - transistor invented in Bell Labs 1951 - first direct long distance dialing 1962 - first international satellite telephone call 1968 - Carterfone court decision allowed non-Bell equipment to connect to Bell System Network 1970 - permitted MCI to provide limited long distance service in competition to AT&T. 1984 - deregulation of AT&T 1980s - public service of digital networks 1990s - cellular telephones commonplace
9 Phases of Telecommunications Development Telegraph & Telephone (19 th century) Satellite communications (1960s) Digital communications (1980s) Internet age (1990s) Wireless communications (1990s) 21 st century? Trends: From wired to wireless, from analog to digital, from voice communicating to data communicating
10 The Invention of Telephone Who invented the telephone? Alexander Graham Bell? Elisha Gray's caveat, as it was filed in the United States Patent Office, February 14, 1876 Elisha Gray's caveat, as it was filed in the United States Patent Office, February 14, 1876 Elisha was a new immigrant, who did not have good English communication skills. The economic condition was too bad to have enough money to pay the patent fee.
11 Semiconductor Industry – the foundation of IT Vacuum tube – Early the 20th century (?) Transistor (Transfer resistor), 1947 at Bell Lab invented by John Bardeen, Walter Brattain, and Willian Shockley (Physics Nobel prize winner in 1956) Integrated circuit, invented by Jack Kilby, TI, in 1959 (Physics Nobel prize winner in 2000)
12 Moore ’ s Law When: 1965 Who: Gordon Moore, co-founder of Intel. Dr. Moore was preparing a speech and made a memorable observation. When he started to graph data about the growth in memory chip performance, he realized there was a striking trend. What: Each new chip contained roughly twice as much capacity as its predecessor, and each chip was released within 18-24 months of the previous chip. An Analogy: If this trend were applicable to airline industry, the plane would cost $500, weigh a few pounds, travel around the world in 20 minutes.
13 Analyses Moore ’ s minimum cost 1962 – 12 components/chip 1965 – 50 components/chip 1970 – 10% of the cost in 1965 per transistor 1975 – 65,000 components/chip The speed growth is faster than size reduction, because there has been a rapid increase in clock frequency. Kuzweil (1999) pointed out that the doubling of processing power started earlier: 1908 (Hollerith Tabulator) 1911 (Monroe Calculator) 1946 (ENIAC) 1951 (Univac I) 1959 (IBM 7090)
15 Internet, Intranet and Extranet The Internet: a network of networks servicing the users worldwide Intranet: an organization's private network that uses Internet technology Extranet: The intranet that some of its functions are accessible to the organization's business partners
16 The Internet Three aspects of the Internet evolution Capacity growth Application and traffic growth Internet policy change
17 Internet Capacity ARPANET (1969): The Internet was started by the U.S. Department of Defense as a network of four computers. - 1974, 62 hosts - 1983, 1000 hosts - 1989, decommissioned NSFNET (1986): Built up by National Science Foundation with a 3-tier structure - 1987, 10,000 hosts in the Internet, 1000 in BITNET - 1988, upgraded to T1 (1.544 Mbps). - 1991, upgraded to T3 (45Mbps) - 1995, decommissioned vBNS (1995): 622Mbps in 1995 vBNS+ vBNS+ (now): 2.5 Gbps (or more)
18 Internet Policy and deregulations Originally, commercial traffic was forbidden on the Internet, because the major portions of these networks were funded by the various national governments and research organizations. In the early 1990s, commercial networks began connecting into these networks, opening it to commercial traffic.
19 Internet Hosts Growth (Recent statistics)Recent statistics July 1999: 56,218,000 Internet hosts January 2000: 68,862,283 Internet hosts July 2000:86,509,613 Internet hosts January 2001:113,873,000 Internet hosts (MIDS)MIDS Now: ?
20 Internet Addresses Anyone with access to the Internet can communicate with any computer on the Internet. Addresses consist of two parts, the computer name and its domain. computer.domain Each domain has an addressing board that assigns addresses for its domain.
21 Internet Domain Names Domain Names EDU COM GOV MIL ORG NET Country Codes CA (Canada) AU (Australia) UK (United Kingdom) DE (Germany) FR (France) CN (China) IN (India) MX (Mexico)
22 Components of a Network Server (or Host computer) Central computer in the network, storing data or software that can be accessed by the clients. Client The input/output hardware device at the other end of a communications circuit. Circuit The pathway through which the messages travel. Peer-to-peer networks Do not need a server or host, but are designed to connect similar computers which share their data and software with each other.
24 Types of Networks Networks can be classified in many different ways. One of the most common is by geographic scope: Local Area Networks (LAN) Backbone Networks (BNs) Metropolitan Area Networks (MANs) Wide Area Networks (WANs)
26 Types of Networks Local Area Networks (LAN) A group of microcomputers or other workstation devices located in the same general area and connected by a common circuit. Covers a clearly defined small area, such as within or between a few buildings, Support data rates of 10 to 100 million bits per second (Mbps).
27 Types of Networks Backbone Network (BN) A larger, central network connecting several LANs, other BNs, metropolitan area networks, and wide area networks. Typically span up to several miles. Support data rates from 64 Kbps to 45 Mbps.
28 Types of Networks Metropolitan Area Network (MAN) Connects LANs and BNs located in different areas to each other and to wide area networks. Typically span from 3 - 30 miles. Supports data rates of 100 to 1000 Mbps.
29 Types of Networks Wide Area Network (WAN) Connects BNs and MANs and are usually leased from inter-exchange carriers. Typically span hundreds or thousands of miles. Supports data rates of 28.8 Kbps to 2 Gbps.
30 *Telecommunication Standards Organizations International Telecommunications Union - Telecommunication Standardization Sector (ITU-TSS). Formerly called the Consultative Committee on International Telegraph and Telephone (CCITT) International Organization for Standards (ISO). Member of the ITU, makes technical recommendations about data communications interfaces. American National Standards Institute (ANSI) Institute of Electrical and Electronics Engineers (IEEE) Internet Engineering Task Force (IETF)IETF Electronic Industries Association (EIA) National Institute of Standards and Technology (NIST) National Exchange Carriers Association (NECA) Corporation for Open Systems (COS) Electronic Data Interchange -(EDI) of Electronic Data Interchange for Administration Commerce and Transport (EDIFACT).
31 *Internet Engineering Task Force A protocol proposed by a vendor IETF working group study the proposal IETF issues a request for comment (RFC) IETF reviews the comments IETF proposes an improved RFC The proposed standard becomes a draft standard if two or more vendors adopt it The RFC becomes a proposed standard