Transcript ectelecom06
MD253 / MK253 Electronic Commerce April 19, 2006 Telecom How the Internet Works Telecommunication Markets Issues Covered • How the Internet Works – IP addresses, TCP/IP, packet switching, and why you should care • Telecom markets – RBOCs, Cable, CLECs, VoIP, and more – Crushing monopolies, shifting billions in wealth The Transmission Speed Crib Sheet • 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 Tbps – terabit, trillions of bits per second (a.k.a wicked fast) 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 (others @ BC: agora, www) domain user ID name, top level domain directory case sensitive file The DNS & IP Addresses • IP Address – Unique number identifying Internet computers. Expressed as four numbers between 0 and 255. – ex: www.bc.edu = 136.167.2.96 (32 bit address) – IPv6: 128 bit addressing, more efficient/faster, secure • DNS - Domain Name Service – A distributed database used to translate host/domain names, into Internet Protocol (IP) Addresses. • Registry of an Internet domain name: – for com, net, org, over 60 firms (see icann.org for list) – for country-specific domains (.jp,.uk, .tv) fees vary widely (see icann.org for list) Network Interconnections dial-in web server www2.bc.edu users (56.6 Kbps) modem pool R dorm users dorm LAN class/office users office LAN wireless BC Campus Network Backbone (1 Gbps) (IP #s 136.167.xxx.xxx domain) Internet Leased Line through our ISPs (100 Mbps) The Internet stanford.edu google.com whitehouse.gov local ISP 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. Packet Traffic • What’s in a packet? – source address – destination address – error checking (checksum) – time to live – options (timestamp, record route, etc.) – your data! A Packet Switched Network at Work packet1 R 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... packet1 packet2 packet2 R packet3 packet3 R R = router R packet1 R packet2 packet2 packet3 packet3 E-mail message: Prof. Gallaugher, I just wanted to let you know ... US Internet Infrastructure Portions of the Abilene Intenet2 Backbone Circuit vs. IP Telephony Circuit Switching Guaranteed QoS (quality of service) Internet VoIP (e.g. Vonage, AT&T CallVantage, Skype) packets over the Internet, variable QoS The Internet Private Network VoIP (e.g. corporate VoIP) packets over private network, improved QoS Private IP Network Words from the Powerful VoIP is the most significant paradigm shift in the entire history of modern communications since the invention of the telephone. Former FCC Chair Michael Powell Employees ask me what I’m most excited about and I tell them Voice over the Internet. It is going to be a really big deal for us. Time Warner CEO Richard Parsons