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MD703

MD703. Internet & Telecom Basics How the Net Works Key Technologies IP Telephony Solving the Last Mile Problem Speed & Ubiquity Developments. What is the Internet?. A Network of Networks TCP/IP - standard protocol for routing & transport A medium of exchanging all form of digital data

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MD703

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  1. MD703 Internet & Telecom Basics How the Net Works Key Technologies IP Telephony Solving the Last Mile Problem Speed & Ubiquity Developments

  2. What is the Internet? • A Network of Networks • TCP/IP - standard protocol for routing & transport • A medium of exchanging all form of digital data • text, graphics, audio, video, programs, faxes • An infrastructure for various services • e-mail (electronic mail) • WWW (world wide web) • FTP (file transfer protocol) • UseNet newsgroups, PointCast, games, EDI, etc.

  3. Transmission Speeds • Bandwidth • measure of transmission speed / capacity • Bits & Bytes • bit - smallest form of computer memory - 1 or 0 • byte - 8 bits, roughly 1 character (Latin alphabet) • How do we measure speeds? • bps - bits per second • Kbps - kilobit, thousands of bits per second • Mbps - megabit, millions of bits per second • Gbps - gigabit, billions of bits per second

  4. How Many People Use the Net? • We don’t know • Nua’s best guess - about 201 million at 9/99 • Breakdown: Source: nua.ie, Sept. 99

  5. Anatomy of a URL • URL • Uniform Resource Locator (web address) http://www2.bc.edu/~gallaugh/directory/file.html application protocol (http is assumed by current browsers). Others: FTP, NNTP host computer (others @ BC: agora, www) domain name, top level domain user ID directory file case sensitive

  6. The DNS & IP Addresses • IP Address • Unique number identifying Internet computers. Expressed as four numbers between 0 and 255. • ex: infoeagle.bc.edu = 136.167.2.241 (32 bit address) • IPv6: 128 bit addressing, more efficient/faster, secure • DNS - Domain Name Service • A distributed database used to translate domain names, into Internet Protocol (IP) Addresses. • Registry of an Internet domain name: • currently in the US for $70 for two years (www.internic.net)

  7. Network Interconnections dial-in users (56.6 Kbps) dorm users office users web server www2.bc.edu modem pool dorm LAN office LAN BC Campus Network Backbone (10 Mbps) (IP #s 136.167.xxx.xxx domain) Internet Leased Line through CW (4.5 Mbps, $8k/mo.) The Internet microsoft.com local ISP whitehouse.gov

  8. TCP/IP • TCP/IP - the Internet’s common language • TCP - Transmission Control Protocol. Breaks up transmissions (e-mail messages, web pages, etc.) into packets of no more than about 1500 characters each, checks the integrity of incoming packets, and reassembles packets on the other end • IP - Internet Protocol. Routes packets.

  9. Packet Traffic • What’s in a packet? • source address • destination address • error checking (checksum) • time to live • options (timestamp, record route, etc.) • your data!

  10. R R R R R R A Packet Switched Network at Work packet1 E-mail message: Prof. Gallaugher, I just wanted to let you know that I got a job based on the stuff I learned in your class... E-mail message: Prof. Gallaugher, I just wanted to let you know ... packet1 packet2 packet2 packet1 packet3 packet3 packet2 packet2 packet3 packet3 = router

  11. US Internet Infrastructure Watch Cable & Wireless’s backbone traffic at: traffic.cwusa.com Source: lbrandt@nsf.gov

  12. TraceRoute from BC to Hawaii 1 cs7513-honolulu.aloha.net (204.94.112.38) 1.481 ms 1.084 ms 0.942 ms 2 207.170.197.201 (207.170.197.201) 72.109 ms 71.315 ms 73.781 ms 3 sl-gw4-sea-5-0-T3.sprintlink.net (144.228.96.9) 75.242 ms 79.062 ms 77.557 ms 4 sl-bb1-sea-0-0.sprintlink.net (144.228.90.1) 79.245 ms 74.64 ms 75.174 ms 5 core2-hssi3-0.Seattle.mci.net (206.157.77.153) 76.262 ms 75.853 ms 77.16 ms 6 bordercore1.Boston.mci.net (166.48.60.1) 145.921 ms 142.257 ms 142.892 ms 7 boston-college.Boston.mci.net (166.48.62.14) 154.438 ms 148.711 ms 151.135 ms 8 Infoeagle.bc.edu (136.167.2.146) 150.337 ms 149.579 ms 154.07 ms

  13. TraceRoute from BC to Albany, NY 1 be102 (169.226.4.1) 2 ms 1 ms 1 ms 2 at-gw3-alb-1-0-T3.nysernet.net (169.130.23.5) 2 ms 3 ms 2 ms 3 at-gw2-alb-0-0.nysernet.net (169.130.20.2) 2 ms 3 ms 3 ms 4 at-gw1-syr-1-0-T3.nysernet.net (169.130.1.22) 6 ms 4 ms 4 ms 5 at-gw1-ith-0-0-T3.nysernet.net (169.130.1.42) 7 ms 7 ms 7 ms 6 at-gw2-ith-0-0.nysernet.net (169.130.60.2) 7 ms 7 ms 7 ms 7 at-bb1-pen-5-0-0-T3.nysernet.net (169.130.1.121) 20 ms 20 ms 20 ms 8 sl-bb6-pen-6-0-0.sprintlink.net (144.228.60.21) 21 ms 23 ms 20 ms 9 core4-hssi5-0.WestOrange.mci.net (206.157.77.105) 25 ms 26 ms 25 ms 10 bordercore1.Boston.mci.net (166.48.60.1) 317 ms 54 ms 110 ms 11 boston-college.Boston.mci.net (166.48.62.14) 36 ms 37 ms 36 ms 12 Infoeagle.bc.edu (136.167.2.146) 36 ms 37 ms 36 ms

  14. TCP vs. UDP TCP - perfect transmission is critical (e.g. e-mail) TCP will request packets that are lost or damaged The Internet UDP = User Datagram Protocol UDP - low latency is critical (e.g. RealAudio, Video, packet streaming) Latency matters - UDP will ignore packets that don’t arrive on time or in good shape The Internet

  15. Circuit vs. IP Telephony Circuit Switching 64 Kbps circuit, guaranteed QoS (quality of service) Internet Telephony (e.g. Net2Phone) packets over the Internet, variable QoS The Internet IP Telephony over Private Networks (e.g. Qwest) packets over private network, improved QoS Private IP Network

  16. Transmission Speeds • The last mile problem • access to many consumers & businesses may be slow (e.g. 28.8 Kbps modem speeds) • The contenders • faster modems - (at ISP and user end; 56 Kbps) • ISDN - (e.g. BellAtlantic; up to 128 Kbps) • GEO Satellite (e.g. DirectDuo; 400 Kbps download) • LMDS (e.g. CellularVision; 500 Kbps download) • Cable Modems (e.g. MediaOne; 1.5 Mbps download) • ADSL (e.g. AmeriTech; 1.5 - 7 Mbps download)

  17. Bandwidth Bonanza(download speeds only)

  18. Satellite Schemes • GEO • Spaceway from Hughes (2003, 2-6 Mbps) • LEO • Teledesic (2004, 2 to 64 Mbps) Graphic from Byte

  19. Fostering Speed & Ubiquity • Caching servers • get content closer to customers • e.g. Akamai, Inktomi, Digital Island • Dense Wave Division Multiplexing • prisms split fiber optic signal • Wireless Access • WAP, i-mode, emerging 3G standards • Integration of Wireless Devices • Bluetooth

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