1. CPS 356: Introduction to Computer Networks Lecture 1: Introduction and course overview Xiaowei Yang xwy@cs.duke.edu

2. Welcome back! Hope you had a great holiday break!

3. Today Course introduction Course forecast – What we will be covering

4. Who should be taking this class? Curious about how things work – A lot of internals of networking Loves to build things – Programming labs

5. Why? You use it (the Internet) every day. – Youtube, DNS, Skype, Facebook, Gmail Multi-billion dollar companies built on it – Google, Facebook – Chances you’ll develop some network applications in the future are high Changing the way people live – Network development in developing countries Massive online learning, Internet clinics, the fisherman story Fun applications – Online games, social networking, video streaming, … – The next one may be yours!

6. Course goals Goals: principles that underlie the design of computer networks and network protocols – Division of labor: smart vs dumb networks – Soft state vs hard state – Packet switching vs circuit switching – Layered vs integrated designs – Structured overlay vs unstructured overlay

7. Why design principles are important System building does not have just one answer Help you acquire a good taste – Myspace vs Facebook – Google vs all search engines before it

8. Prerequisites Good knowledge of C/C++ – Labs are done in C/C++ – Some knowledge of socket programming from CPS 310

9. Course staff Instructor: Xiaowei Yang – http://www.cs.duke.edu/~xwy/ http://www.cs.duke.edu/~xwy/ – Main research interests: network architectures and protocols, network security, distributed systems TA: Hongze Zhao – https://www.cs.duke.edu/~hongze/

10. Recommended Textbook Larry L. Peterson, Bruce S. Davie, Computer Networks: A Systems Approach, 5 th Edition, Morgan KaufmannComputer Networks: A Systems Approach – Available from bookstore, amazon – A view as a system builder, not a user – 4 th is okay

11. Website: important http://www.cs.duke.edu/courses/spring14/compsci356/ Syllabus – Book chapters related to lectures – Pointers to external papers for topics – Read before class for discussion – Assignments and due dates – Lectures All subject to change. Reload before checking

12. Discussion forum Piazza? What do you suggest?

13. Contact Us: We are here to help you Office hours – TA: Fridays 10am-noon @ North 06 – Instructor: Fridays 1:30-3:30pm or by appointment – All course related topics: compsci356-staff@cs.duke.educompsci356-staff@cs.duke.edu Grading, questions, homework, labs, exams Within a day Email for meetings outside regular office hours Really urgent – State so in your email – IM: xiaowei@gmail.com (voice mail does not work), zhaohongze@gmail.comxiaowei@gmail.com zhaohongze@gmail.com Unfortunately, no recitation section was scheduled – Do come to office hours – Do communicate with us via email

14. Your work: important Assigned readings in the Syllabus Homework Labs (substantial, but worth your time). Most of them are ~500 lines of code, 20 hours of coding/debugging – Lab 1: simple router – Lab 2: dynamic routing – Lab 3: reliable transport – Lab 4: congestion control Labs contain pre-lab questions that help you understand the basic concepts Labs are distributed with skeleton code and most of them have reference implementations for testing Turn-ins include answers to pre-lab questions, source code, lab reports if we ask for them

15. Collaboration policy Discussion is encouraged Individual assignments must be completed independently Group assignments only need to turn in one copy of the files with group members noted in the submission

16. Late policy All assignments are due at the beginning of the class on the due dates – I may grant extensions if you show up in class The deadline for any assignment can be extended with a 10% penalty per day. – No deadline can be extended by more than two days. – Assignments will NOT be accepted 48 hours after the due date. Tight schedule Extension will delay next assignment – If you are ill: contact the instructor and provide a medical note.

17. Grading policy Class participation and pop quizzes: 20% Labs: 50% – In a group assignment, both students get the same grade for the assignment Exams: 30%

18. Questions?

19. Course outline The fundamentals – Reliable/secure communications over unreliable/insecure channels – Finding paths through the network – Resource sharing – Providing common services to applications Case studies on how to use the network Content distribution, DNS, p2p, social networks, search engines Socket programming

20. The networking field is broad and confusing…

21. A Plethora of Protocol Acronyms? BGP ARP HTTP DNS PPP OSPF DHCP TCP UDP SMTP FTP SSH MAC IP RIP NAT CIDR VLAN VTP NNTP POP IMAP RED ECN SACK SNMP TFTP TLS WAP SIP IPX STUN RTP RTSP RTCP PIM IGMP ICMP MPLS LDP HIP LISP LLDP BFD Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

22. A Heap of Header Formats? Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

23. TCP/IP Header Formats in Lego Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

24. A Big Bunch of Boxes? Router Switch Firewall NAT Load balancer DHCP server DNS server Bridge Hub Repeater Base station Proxy WAN accelerator Gateway Intrusion Detection System Packet shaper Route Reflector Label Switched Router Scrubber Packet sniffer Deep Packet Inspection Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

25. A Ton of Tools? traceroute nslookup ping ipconfig rancid whois tcpdump wireshark NDT iperf dummynet syslog trat snort bro arpwatch mrtg nmap ntop dig wget net-snmp Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

26. What Do Other People Say? “You networking people are very curious. You really love your artifacts.” “In my college networking class I fell asleep at the start of the semester when the IP header was on the screen, and woke up at the end of the semester with the TCP header on the screen.” “Networking is all details and no principles.” Is networking “just the (arti)facts”? Source: http://www.cs.princeton/~jrex/talks/conext-student10.ppt

27. Teaching/Learning about networking can be hard

28. I hope to make it easy for you Emphasis on fundamentals, concepts, and design skills – Headers will be provided in all your quizzes – You’ll pay attention to details in labs Treat everything we learn as design examples – Why they are designed that way? – Is it a success or failure? – Will you do it the same way?

29. The first big question we study: How to design a global computer network

30. What’s a network? Wikipedia: A wide variety of systems of interconnected components are called networks. Examples of networks: what components are connected? – The Internet – Telephone networks – TV networks – Power networks – Sewage networks – Water networks – …. Why do we build networks? – To distribute/transfer something

31. Features of computer networks Generality Carry many different types of data Support an unlimited range of applications – Can you name several Internet applications?

32. What’s the Internet? The Internet is a large-scale general-purpose computer network. – Run more than one application The Internet transfers information between computers. The Internet is a network of networks.

33. What the Internet looks like email WWW phone... SMTP HTTP RTP... TCP UDP… IP ethernet PPP… CSMA async sonet... copper fiber radio... Ethernet ATM Framerelay IP/SONET Ethernet 802.X Wireless Host Tier 1 Tier 2 Tier 3 The Internet BGP RIP, OSFP Distance Vector Link-State Ethernet, CSMA/CD Bridges, Switches, Spanning Tree Bandwidth x Delay TCP Performance Modulation Coding FDMA, TDMA IP Blocks, CIDR, Subnets Longest Prefix Match, Fragmentation, MTU

34. Summary Course introduction – Administrivia – Course outline Next – Network architectures: different styles of building networks