CS641 Advanced Computer Networks Lecture 01 Bhaskaran Raman Department of CSE, IIT Bombay http://www.cse.iitb.ac.in/~br/ http://www.cse.iitb.ac.in/synerg/doku.php?id=public:courses:cs641-autumn10:start
Agenda for Today ● Introductions ● Course structure, outline, and purpose ● Communication: what and how? ● Internet history ● Internet design and architecture ● OSI layering
Enter the World of Communication Networks Picture of the Internet, from the Internet
Communication: what and how? ● Q: Comm. defn., reqmts., design criteria ● Communication: The exchange of thoughts, messages, or information, as by speech, signals, writing, or behaviour. ● Requirements for communication – Medium + Energy, Protocol ● Design goals/criteria – Reliability, Security, Efficiency (time, cost, energy), etc...
Communication networks ● Q: examples of communication networks ● Before the electronic age – Using doves/pigeons – Smoke signals ● Postal system ● Telegraph ● Telephone network ● Internet ● Cellular/Wireless
History of the Internet ● 1961-62: Packet-switching as a concept ● 1969: Four host computers on ARPANET ● 1972: E-mail application launched ● Network Control Protocol (NCP) used in ARPANET ● 1980s: LANs, PCs, Workstations ● Until 1985: Internet used by researchers/developers
History (continued) ● Networks from DoE, NASA, NSF, AT&T ● NSFNET backbone was created ● Privatization: 1985-1995 – 6 nodes (56kbps links) to 21 nodes (45Mbps links) ● Steady exponential growth for 15 years – In bandwidth, number of hosts, total traffic, etc. ● http://www.isc.org/ds/
5 0 0 2 f o s a t e n r e t n I Picture courtesy Google Source: http://www.caida.org/
World Population 56% 14% n o 1% i ) t 7 a 0 l 8% u 0 5% p 3% 2 12% o Africa Asia Europe f P o Middle East North Latin America America/Car d s ibbean a l r Oceania / ( o Australia W Source: http://www.internetworldstats.com/
Internet users of the world s 37% r e 4% s 2% U ) 7 0 t 27% 9% e 0 n 2 3% 19% r Africa Asia Europe e f o Middle East North Latin t n America America/Car s ibbean I a d Oceania / ( Australia l r o W Source: http://www.internetworldstats.com/
Internet penetration n WORLD TOTAL 19% o i t 55% Oceania / Australia a ) 7 r t 0 21% Latin America/Caribbean e 0 n 2 70% North America e f P o 17% Middle East t s e 42% Europe a n ( r 12% e Asia t n 5% Africa I 0% 10% 20% 30% 40% 50% 60% 70% 80% Source: http://www.internetworldstats.com/
Internet usage growth : h t w WORLD TOTAL 245% o Oceania / Australia 150% r G 7 0 541% Latin America/Caribbean e 0 g 2 117% North America a - 0 s 920% Middle East 0 U 0 222% Europe 2 t e n 302% Asia r e 875% Africa t n 0% 100% 200% 300% 400% 500% 600% 700% 800% 900% 1000% I Source: http://www.internetworldstats.com/
Internet in Different Regions Population Internet Users, Penetration Use Growth Region (2007 Est.) Latest Data (% Population) (2000-2007) India 60000000 1129667528 5.30% 1100.00% China 162000000 1317431495 12.30% 620.00% Japan 87540000 128646345 68.00% 85.90% United States 215088545 301139947 71.40% 125.60% Brazil 39140000 186771161 21.00% 682.80% Germany 50426117 82509367 61.10% 110.10% Source: http://www.internetworldstats.com/
What is a Communication Network? Communication Communication Network Network Icons courtesy Google
Network Components: Hosts Communication end-points – PCs, Workstations, PDAs, Cellphones, Servers Pictures courtesy Google
Interface Cards Attach the host to the link Pictures courtesy Google
Links Carry signals from one place to other place(s) Cat5-twisted pair Co-axial Fiber Optics Pictures courtesy Google
Hubs/Switches/Routers Switch Hub Router Pictures courtesy Google
Types of Networks Inter-node distance Type of network <1m Multi-processor network 1-10m Personal Area Network 10m-1km Local Area Network 10-100km Metropolitan Area Network 100-1000km Wide Area Network 10000-100000km Internet >100000km Inter-planetary Internet
Upcoming Topics ● Internet design goals ● The end-to-end principle – How to separate functionalities into layers? – Designated reading [SRC84] ● Routing, ISPs, BGP...
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