Telecommunications & The Internet Basic Telecom Model Computer Computer Channel interface Communication Channel Channel interface Typical Home Telecom Model Computer Digital signals Computer Digital signals Modem Modem Audio Phone Lines Analog signals Channels • • • • • Twisted wire (twisted pair) Coaxial Cable Fiber Optics Microwave Newer Wireless Twisted Pair • • • • • Low cost easy to work with installed infrastructure crosstalk 300bps to 100Mbps • “This modem is 56Kbps capable. However, current regulations limit download speeds to 53Kbps,” the fine print from a typical modem advertisement. DSL • • • • Uses existing twisted pair 256Kbps to 40Mbps Loop length max about 18,000 ft. More correctly ADSL (Asymmetric Digital Subscriber Line) with download speeds different from upload speeds. Coaxial Cable • More expensive • harder to work with • not as extensive an existing infrastructure – cable TV companies are changing this • 56Kbps to 550Mbps Fiber Optics • • • • Very expensive difficult to work with existing infrastructure limit to backbones 500Kbps to 30Gbps Microwave • Not as expensive as land lines • Limited to line of site, (towers) – reasonable infrastructure • Satellite bounce, increases expense – geo-synchronous (22,000 miles) – low earth orbit (cheaper, lower power) • 256Kbps to 100Mbps Newer Wireless – Cellular – mobile data networks – personal communications services (PCS) – note: pagers & PDAs are not channels, they would be nodes on one end of a channel Transmission Speed • BPS, bits-per-second, the amount of information that can be transmitted through a channel • BAUD - a binary event, a signal change from positive to negative or vice versa. Speed II • At higher speeds a single signal change can transmit more than one bit at a time, so the bit rate will generally be higher that the baud rate. • Transmission capacity is a function of the frequency, higher frequency means higher capacity More Speed • Bandwidth = range of frequencies that a channel can support (difference between highest and lowest frequency). • Greater range means greater bandwidth. • Greater bandwidth means greater transmission capacity. Faster Yet • Bandwidth is like pipe diameter. • Larger diameter pipes can transmit more water in a given period of time. • Personal Communication Services, PCSs, have a greater bandwidth than fiber optics. Communications Processors Computer Front End Processor Controller Channel T Multiplexer PC PC T T C h a n n e l CPU Concentrator T PC Network Topology • Star Network C C C P C • Bus Network C C C P C • Ring Network P C C C C Networks • Local Area Network, LAN • Wide Area Network, WAN • Value Added Network, VAN Network Terms • • • • • File server Print server Gateway - connects dissimilar networks Bridge - connects similar networks Routers - connects networks & directs traffic • Similar networks = same network protocols Transmission on LANs • Token Ring – can talk only when you have the token – cost more than Ethernet – better for high volume traffic • Ethernet – talk whenever you want – send again if collision – works best with low volume traffic Chapter 8 20 Transmission on WANs & VANs • Packet Switching – – – – message broken into packets packets may take various routes message reassembled at destination allows load balancing on channels • Frame Relay – like packet switching, no error correction The Internet • What is the Internet? • Who owns the Internet? • Why does the Internet exist? Evolution of the Internet • 1970 ARPANET - 15 nodes • 1972 first email • 1982 TCP/IP becomes internet standard – Transmission Control Protocol/Internet Protocol • 1984 ARPANET - 1,000 nodes • 1986 NSF-Net backbone on ARPANET • 1987 ARPANET - 10,000 nodes Evolution of the Internet • 1988 - businesses begin to connect to system for research purposes • 1989 ARPANET - 100,000 nodes • 1989 link email between CompuServe and ARPANET • 1990 ARPANET becomes the Internet Public Networks CompuServe • 1969 started in Cleveland with single computer • 1979 provided first email • 1980 started national service • Mid-1980s largest online service • 1995 3 Million users • 1997 purchased by AOL Public Networks Prodigy • 1986 pilot in Atlanta, Hartford, San Francisco • 1988 national service launched • 1994 1st to offer WWW access • 1999 Prodigy Classic discontinued (209,000 members) Public Networks AOL • • • • • 1991 AOL for DOS 1993 AOL for Windows 1997 bought CompuServe 1999 10 Million users Estimated to have distributed over 1 Billion discs of over 1,000 different disk/CD styles Internet Statistics • http://www.internetworldstats.com/stats.htm – User Counts, updated daily • http://whois.sc/internet-statistics/ – Domain Counts, updated daily The Keys to Internet Growth • 1991 WAIS and Gopher provide Internet search and navigation • 1992 WWW hyperlink software released • 1992 NSF relaxes its restriction on commercial Internet traffic • 1992+ explosive growth in usage Internet Capabilities • Communications – – – – E-mail Usenet Chatting Telnet • Information Retrieval – – – – Gopher Archie WAIS FTP http://sunland.gsfc.nasa.gov/info/guide/Using_archie_Today.html World Wide Web • Set of standards for storing, retrieving, formatting, and displaying information using a client/server architecture • Hypertext markup Language (HTML) • browser • search engines Putting It All Together AT&T Level 3 Centurylink I29 Consumer Cable One Consumer Consumer Some Upper Tier Providers • • • • • • AT&T Bell Atlantic Bell South Cable and Wireless Cable One GTE • • • • • • IBM MCI Pacific Bell QUEST Sprint US West Tier 1 Networks • The largest backbones on the Internet: • Centurylink, Telecom Italia, Verizon, Sprint, TeliaSonera International, NTT Communications, Deutsche Telekom, Level 3, AT&T • These top branded backbones only trade peering traffic among themselves. Common Bandwidths • • • • • • • 56K modem 0.056 Mbps ADSL 40 Mbps Cable Modem 50 Mbps T1 1.5 Mbps Ethernet 10 to 1,000 Mbps T3 44.7 Mbps See http://bandwidthplace.com/ Upper Tier Bandwidths OC-x mulitples of 51.85 Mbps • • • • • • OC-3 OC-12 OC-48 OC-96 OC-192 OC-768 155 622 2,488 4,977 9,953 39,812 Mbps Mbps Mbps Mbps Mbps Mbps Organization Benefits of Internet • Reducing Communication Costs – virtual private net • Enhancing Communication and Coordination • Accelerating the Distribution of Knowledge • Facilitating Electronic Commerce Intranets • An internal network based on World Wide Web technology • Firewall – security software to prevent unauthorized access to an intranet • Firebreak – a physical break between the Internet and Intranet Internet Challenges • Security • Technology Problems – – – – incompatibility limited bandwidth telecommunications infrastructure internet specialists • Legal Issues IP Addresses • An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address. IP Address Classes • • • • Class A - 168.212.226.204 supports 16 million hosts on each of 127 networks Class B - 168.212.226.204 supports 65,000 hosts on each of 16,000 networks – NDUS has two Class B addresses • 134.129.xxx.xxx • 134.234.xxx.xxx Eastern ND Western ND • Class C - 168.212.226.204 • supports 254 hosts on each of 2 million networks IPv4 vs. IPv6 • IPv4 – 32 bits used for address – 4,294,967,296 – Addresses not assigned by geographic region (see map) • IPv6 – 128 bits used for address – 340,282,366,920,938,463,374,607,431,768,211,456 – That about 3.7x10^21 addresses per square inch of the earth’s surface – Addresses will be assigned by geographic region IPv4 vs. IPv6 • IPv4 addresses written as four octets (8 bits) separated by periods. – 134.129.67.235 • IPv6 address written as eight 4-digit (16-bit) hexadecimal numbers separated by colons. – 1080:0:0:0:0:800:0:417A Uniform Resource Locator • http://www.ndsu.nodak.edu/ndsu/latimer/index.html#events • • • • • http:// www.ndsu.nodak.edu /ndsu/latimer/ index.html #events communication protocol web server hosting the page path to the page on the host server filename of the page anchor in the page IP & Domain Name Examples • IP: 134.129.67.85 • URL: gdc.busad.ndsu.nodak.edu • IP: 134.129.67.235 • URL: dyn235.minard-67.ndsu.nodak.edu ICANN • Internet Corporation for Assigned Names and Numbers • a private sector, nonprofit organization • responsibility for IP address space allocation, protocol parameter assignment, domain name system management and root server system management functions previously performed under U.S. Government contract • ICANN's diverse board consists of nineteen Directors, nine At-Large Directors, who serve one-year terms and will be succeeded by At-Large Directors elected by an at-large membership organization. None of the present interim directors may sit on the board once the permanent members are selected. IP Address Registries • Regional Internet Registries: • American Registry for Internet Numbers, ARIN • Réseaux IP Européens Network Coordination Centre, RIPE NCC • Asia Pacific Network Information Centre, APNIC • Latin American and Caribbean Internet Addresses Registry, LACNIC Internet Assigned Numbers Authority http://www.iana.org/ • Generic Top-Level Domains – http://www.iana.org/gtld/gtld.htm • ccTLD Database (country codes) – http://www.iana.org/cctld/cctld-whois.htm • IP Address Services – http://www.iana.org/ipaddress/ip-addresses.htm New Top-Level Domain Names (TLDs) • ICANN is accepting applications for new TLDs. – Application window Jan. 12, 2012 to Apr. 12, 2012 – Application fee: $185,000 – Annual fee: $25,000 • Intent is to move towards more descriptive names • Companies (organizations) can create – Brand domains e.g. .pepsi – Generic domains e.g. .car .coke .green • http://mashable.com/2011/06/20/icann-top-level-domains/
