CS641 Advanced Computer Networks Lecture 01 Bhaskaran Raman - - PowerPoint PPT Presentation

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/

Picture courtesy Google

I n t e r n e t a s

• f

2 5

Source: http://www.caida.org/

Source: http://www.internetworldstats.com/

14% 56% 12% 3% 5% 8% 1%

World Population

Africa Asia Europe Middle East North America Latin America/Car ibbean Oceania / Australia

W

• r

l d P

• p

u l a t i

• n

( a s

• f

2 7 )

Source: http://www.internetworldstats.com/

4% 37% 27% 3% 19% 9% 2%

Internet users of the world

Africa Asia Europe Middle East North America Latin America/Car ibbean Oceania / Australia

W

• r

l d I n t e r n e t U s e r s ( a s

• f

2 7 )

I n t e r n e t P e n e t r a t i

• n

( a s

• f

2 7 )

Source: http://www.internetworldstats.com/

Africa Asia Europe Middle East North America Latin America/Caribbean Oceania / Australia WORLD TOTAL 0% 10% 20% 30% 40% 50% 60% 70% 80%

5% 12% 42% 17% 70% 21% 55% 19%

Internet penetration

I n t e r n e t U s a g e G r

• w

t h : 2

• 2

7

Source: http://www.internetworldstats.com/

Africa Asia Europe Middle East North America Latin America/Caribbean Oceania / Australia WORLD TOTAL 0% 100% 200% 300% 400% 500% 600% 700% 800% 900% 1000%

875% 302% 222% 920% 117% 541% 150% 245%

Internet usage growth

Internet in Different Regions

Region

1129667528 60000000 5.30% 1100.00% 1317431495 162000000 12.30% 620.00% 128646345 87540000 68.00% 85.90% 301139947 215088545 71.40% 125.60% 186771161 39140000 21.00% 682.80% 82509367 50426117 61.10% 110.10% Population (2007 Est.) Internet Users, Latest Data Penetration (% Population) Use Growth (2000-2007)

India China Japan United States Brazil Germany

Source: http://www.internetworldstats.com/

What is a Communication Network?

Communication Network Communication 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) Fiber Optics Co-axial Cat5-twisted pair

Pictures courtesy Google

Hubs/Switches/Routers

Hub Switch 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...