1) Goals & Motivation

Focus of The Course:

• Three Networking Topics :

1. Distributed Systems (working on various apps)
2. Networking (working on packet level)
3. Communication (working on signal and system level)

• Here we will learn and understand the concept of Networking.

The Main Point:

1. To learn how the Internet works »
   – What really happens when you “browse the web”?
   – What are TCP/IP, DNS, HTTP, NAT, VPNs, 802.11 etc. anyway?
2. To learn the fundamentals of computer networks

Why learn about the Internet?

1. Curiosity »
2. Impact on our world »
3. Job prospects!

From this experimental network … ARPANET ~1970

To this! Internet ~2005

• An everyday institution used at work, home, and on-the-go
• Visualization contains millions of links

Attribution: By The Opte Project [CC-BY-2.5], via Wikimedia Commons

Internet – Economic impact

• An engine of economic growth

          – Advertising-sponsored search like Google

          – “Long tail” online stores like amazon

          – Online marketplaces like ebay

          – Crowd-sourcing

The Main Point (2)

1. To learn how the Internet works
2. To learn the fundamentals of computer networks
   – What hard problems must they solve?
   – What design strategies have proven valuable?

Why learn the Fundamentals?

1. Apply to all computer networks
2. Intellectual interest »
3. Change / reinvention »

Fundamentals – Intellectual Interest

•  Example key problem: Reliability!

           – Any part of the Internet might fail
           – Messages might be corrupted
           – So how do we provide reliability?

• Reliability solutions

          – Codes to detect/correct errors
          – Routing around failures ...

• Key problems with example solutions::

1. Reliability despite failures :
   Codes for error detection/correction
   Routing around failures
2. Network growth and evolution :
   
   Addressing and naming
   Protocol layering
3. Allocation of resources like bandwidth :
   
   Multiple access
   Congestion control 
4. Security against various threats :
   

   Confidentiality of messages

   Authentication of communicating parties
   
   

Fundamentals – Reinvention

• The Internet is constantly being re-invented!– Growth over time and technology trends drive upheavals in Internet design and usage »

• Today’s Internet is different from yesterday’s– And tomorrow’s will be different again– But the fundamentals remain the same

• At least a billion Internet hosts and growing …

• Examples of upheavals in the past 1-2 decades ::

                Growth / Tech Driver-------------Upheaval

                Emergence of the web-------------Content Distribution Networks

                Digital songs/videos---------------Peer-to-peer file sharing

                Falling cost/bit--------------------Voice-over-IP calling

                Many Internet hosts-------------- IPv6

                Wireless advances-----------------Mobile devices

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