1. CS 4119: Computer Networks Henning Schulzrinne Dept. of Computer Science Columbia University http://www.cs.columbia.edu/~hgs

2. Why learn about computer networks? Almost all modern software applications are distributed  from enterprise applications to video games General useful principles:  dealing with asynchronicity  unreliable components  predictable end systems  (network) life is random and unpredictable  work with other implementations that you have never met before Theory:  congestion control  routing How does the world really work?  email, the web, P2P applications, DSL, … Learning to create professional-grade network applications  not just use libraries as black boxes

3. CS4119 as Foundation Lots of Columbia Computer Science classes build on this:  COMS 4180 Network Security  COMS 6181 Advanced Internet Services  COMS 6998 Advanced Internet Routing  COMS 6180 Modeling & Performance Evaluation  COMS 6125 Web-enhanced Information Management  ELEN 6950 & 6951 Wireless & Mobile Networks  + projects in a variety of research groups

4. Course Information Introductory (first) course in computer networking Who is this course for?  Undergraduates (senior), MS students, first-year PhD students Prerequisites:  Algorithms, operating systems, programming skills in C Course materials:  text: Computer Networking: A Top Down Approach Featuring the Internet, Jim Kurose & Keith Ross, Addison Wesley, 3rd edition 2005  WWW readings  Class notes

5. Course Information (more) Class WWW site: http://www.cs.columbia.edu/4119 Web Bulletin Board Workload written homework assignments420% programming assignments320% lab assignments1-210% midterm120% final exam130%

6. A bit about myself UMass Amherst, Bell Labs, GMD Fokus (now Fraunhofer), Columbia Research interest in networking (IRT research group at Columbia)  performance and reliability  multimedia systems  security Active in Internet protocol standardization  IETF

7. Part 1: Introduction What is the Internet? What is a protocol? The network edge, core, and access networks Physical media Delay and loss in Packet-Switched Networks Protocol layers, service models Internet backbones, NAPs and ISPs Standardization A brief history of computer networking & Internet

8. Part 2: Application Layer Principles of application-layer protocols The World Wide Web: HTTP File transfer: FTP Electronic mail in the Internet The Internet's directory dervice: DNS Socket programming

9. Part 3: Transport Layer Transport-layer services and principles Multiplexing and demultiplexing applications Connectionless transport: UDP Principles of reliable of data transfer TCP case study Principles of congestion control TCP congestion control

10. Part 4: Network Layer Introduction and network service model Routing principles Hierarchical routing IP: the Internet Protocol Routing in the Internet What is inside a router?

11. Part 5: Link Layer & LANs Introduction, services Error detection and correction Multiple access protocols and LANs LAN addresses and ARP Ethernet Hubs, Bridges and Switches Wireless LANs: IEEE 802.11 PPP: the Point-to-Point Protocol ATM

12. Time permitting Security  see Network Security Multicast Overlay and peer-to-peer networks Multimedia  see Advanced Internet Services