e Commerce Technology 20 751 Lecture 2 e

e. Commerce Technology 20 -751 Lecture 2: e. Commerce Infrastructure

Projected Internet Host Count ADVERTISED HOST = DOMAIN NAME IN DNS TABLE 1 BILLION AUG. 2005 Historical 93 MILLION OCT. 2000 10 MILLION JAN. 1996 100 MILLION JAN. 2001 Projected 1 MILLION JUL. 1992 SOURCE: NGI

Bandwidth Review • Bit (b) = a unit of information, 0 or 1 – 10 bits can represent 1024 different messages – 20 bits represent > 1 million – 30 bits > 1 billion messages • The bandwidth of a communication channel = number of bits per second it transmits • All channels have limited bandwidth • One byte (B) = 8 bits (an octet) • Transmitting 1 MB at 56 K bps takes 143 sec. • 1 GB = gigabyte takes 40 hours – at 7 Mbps 19 minutes; at 1 Gbps takes 8 seconds) • Latency = delay from first bit transmitted to first received

Bandwidth of a Truck • Semi Tractor-Trailer 30’L x 10’H x 8’W 2500 ft 3 • DVDs (Digital Videodisks) – @5 GB each, 2000 GB (2 terabytes)/ ft 3 – Semi holds 5 million GB = 5 petabytes (enough to store every book ever published) • Pittsburgh - San Francisco 3000 miles – @ 50 miles/hour = 60 hours 200, 000 seconds – Bandwidth 25 GB / second 200 gigabits/sec 200 times the bandwidth of gigabit Ethernet! • Problem: latency = 60 hours

BANDWIDTH 1 terabit APPLICATION TECHNOLOGY Experimental All U. S. telephone conversations simultaneously 1 gigabit Full-motion HDTV OC 12 = 622 Mb FDDI OC 3 = 155 Mb Virtual Reality, Medical Imaging 802. 11 b = 11 Mb DSL ~ 7 Mb Video Conferencing, Multimedia Streaming Video + Voice 802. 11 = 2 Mb T 1/E 1 Browsing, Audio ISDN New Modem 56 K “Fast” modem ADSL ISDN 128 K E-mail, FTP 19. 2 Old Modem Telnet 4. 8 Human speech = 30 bps Paging Fiber T 3/E 3 T 3 = 44. 7 Mb T 1 = 1. 544 Mb Gigabit Ethernet Copper

Optical Fiber Capacity Growth 1983 -2002 World record January 2002 Alcatel: 5 terabits in one fiber for 15 x 100 kilometers 1, 400 OC-192, 128 l 1, 200 1 Terabit = 1, 000 Single Fiber Capacity (Gigabits/sec) OC-192, 80 l 800 600 OC-192, 48 l 400 OC-192, 32 l OC-48, 96 l OC-192, 16 l OC-48, 40 l OC-192, 2 l OC-192 200 20 -751 ECOMMERCE TECHNOLOGY SUMMER 2002 93 19 94 19 95 19 96 19 97 19 98 19 99 19 92 19 91 19 90 19 89 OC-48 19 87 1. 7 Gb 19 19 86 565 Mb 85 19 19 19 83 0 84 135 Mb COPYRIGHT © 2002 MICHAEL I. SHAMOS

LINK Population Per Internet Host Computer

LINK

Structure of the Internet NAP Europe Backbone 1 NAP Backbone 4, 5, N Japan Regional A Backbone 2 NAP Backbone 3 Australia Regional B MAPS UUNET MAP SOURCE: CISCO SYSTEMS

Internet I Network Architecture SOURCE: LAUDON & TRAVER, p. 126

Connecting to Internet Backbone Y E N O M SOURCE: HOWSTUFFWORKS. COM 20 -751 ECOMMERCE TECHNOLOGY SUMMER 2002 COPYRIGHT © 2002 MICHAEL I. SHAMOS

Satellite Access (Inter. Sat. Com)

Circuit Switching v. Packet Switching SOURCE SWITCH SWITCH SWITCH SWITCH DESTINATION CIRCUIT-SWITCHED NETWORK 20 -751 ECOMMERCE TECHNOLOGY SWITCH DESTINATION PACKET-SWITCHED NETWORK SUMMER 2002 COPYRIGHT © 2002 MICHAEL I. SHAMOS

Network Topologies • More than two computers causes complications: 1 2 3 4 LAN BUS TOPOLOGY 5 LAN = LOCAL AREA NETWORK • Each machine on a network must have a unique address • If machine 2 sends a message to machine 4, what tells 1, 3 and 5 to ignore it, but 4 to listen? • Ethernet protocol

Routing Machine 1. 35 wants to send a packet to Machine 3. 249. Machine 2. 16 Routers determine the path the packet will take. Machine 1. 35 Machine 3. 249 B A Router A can send the packet either way NUMBER OF ROUTES ROUTING STATISTICS 20 -751 ECOMMERCE TECHNOLOGY 4. 1 NETWORK 4 & IT’S ROUTER SUMMER 2002 5. 9 COPYRIGHT © 2002 MICHAEL I. SHAMOS

Routers NORTEL 3 COM CISCO 20 -751 ECOMMERCE TECHNOLOGY SUMMER 2002 COPYRIGHT © 2002 MICHAEL I. SHAMOS

Packet Switching (TCP/IP) TCP = TRANSMISSION CONTROL PROTOCOL (Breaks messages into packets and reassembles them) IP = INTERNET PROTOCOL (Moves packets around the Internet) SOURCE: J. DECEMBER

Packet Switching (TCP/IP)

IP Addresses • Machines on the Internet need an addressing scheme (or couldn’t receive packets!) • Each machine has a 32 -bit address assigned by the Internet Corporation for Assigned Names and Numbers (ICANN). • In the U. S. , American Registry for Internet Numbers (ARIN) • In Europe, Réseaux IP Européens (RIPE) • Addresses are written in dotted decimal notation: 128. 2. 218. 2 1000000010 11011010 00000010 • Current max number of IP addresses = 232 ~ 4, 000, 000

Domain Names • IP addresses are inconvenient to remember 128. 2. 218. 2 v. euro. ecom. cmu. edu (fully qualified) • Domain names are alphanumeric aliases for IP addresses. They form a tree structure of FQDNs: ROOT. GOV AMAZON . COM MCKINSEY . MIL YAHOO . NET . EDU CMU PITT . ORG . IT MIT 208. 216. 182. 15 207. 237. 113. 94 GSIA WWW 128. 2. 16. 175 YEN CS ECOM EURO 128. 2. 218. 2 HEINZ DOLLAR PESO 128. 2. 218. 4

URL: Uniform Resource Locator • URL identifies a specific resource on a server in a domain • URL tells what protocol to use to access the resource • URL format: http: //euro. ecom. cmu. edu/program/courses/index. shtml protocol: //domain_name/path_name

URL: Two Hierarchies Spliced euro. ecom. cmu. edu/program/courses/tcr 751 ROOT. GOV AMAZON . COM MCKINSEY . MIL . NET CMU YAHOO GSIA FQDN . EDU YEN CS . ORG PITT ECOM EURO . IT MIT HEINZ DOLLAR PESO 128. 2. 218. 2 ABOUT AFFILIATES HOST DIRECTORY PEOPLE PROGRAM COURSES tcr 751 index. html tcr 753 tcr 770 tcr 870

Browser • Implements HTTP (Hyper. Text Transfer Protocol) – Displays web pages – Access authentication – Caching, freshness control • • Font mapping, e. g. Unicode Compression, decompression Handles multimedia, manages plug-ins Interprets scripts Executes Java applets Maintains cache, history Manipulates cookies

Q&A 20 -751 ECOMMERCE TECHNOLOGY SUMMER 2002 COPYRIGHT © 2002 MICHAEL I. SHAMOS