Lecture #1 (1).pdf

Computer Networks Lecture #1 Welcome This is the Computer Networks course Today.. Introduction to the course Introduction to the Internet Principles Terminologies Trend Course Introduction Course Introduction What is this course about? Learn what the Internet l...

Computer Networks Lecture #1 Welcome This is the Computer Networks course Today.. Introduction to the course Introduction to the Internet Principles Terminologies Trend Course Introduction Course Introduction What is this course about? Learn what the Internet looks like and what design principles have been applied to it Discuss the latest issues and technology in the networking domain. Mainly focuses on the network/link layers (c.f., Data communications has covered the application/transport layer) Prerequisite A bit of programming skill (C / C++) Administrative Information Class hour 15:00 ~ 16:30 on Mon & Thu Class room #411 in Hanbit Bldg. Textbook & References Textbook Computer Networking A Top-Down Approach, 8th Edition, James F. Kurose, Keith W. Ross, Pearson References Online materials including technical reports, papers, tutorials will be used Grading policy Exams: 70% (35% for midterm and nal, respectively) Project & Homework: 25% Class participation: 5% You will fail this course when Missing more than 10 class hours Cheating in assignment or projects fi Projects Team or individual projects will be provided For the project, you may be supposed to Read a few papers and submit their summaries and critiques Programming assignment (for simulation or empirical studies) Instructor Dohyung Kim Associate professor in Dept. of Computer Science & Engineering Leading “Intelligence in Computer Networking (ICN)” Lab #403 in Hanbit bldg. Email: [email protected] https://www.icnlab.dev Introduction to the Internet Telephone network vs. Internet Telephone network Circuit switching First WAN (wide area network) Packet switching Communication is enabled without dedicated channels!! Telephone network vs. Internet Internet History Telephone network vs. Internet Network Performance Bandwidth Maximum rate of data transfer across a given network path Latency The amount of time it takes to deliver some data from the source to the destination across the network “Latency lags bandwidth” - David A. Patterson Bandwidth vs. Latency  Performance metric Flow completion time How long does it take to complete a tra c ow How long does it take to complete a set of correlated ows (co- ows)? What else? How long does https://www.google.com?q=cool+network take? What is the best video quality I can watch, without the annoying “bu ering”? How to guarantee the per-frame latency (e.g., 20ms) in AR? Not just about performance But also consistent, predictable performance fl ff ffi fl fl Fairness Network Reliability End-to-end argument TCP provides reliable transport What if no reliable transport is provided? Every application that needs reliability has to engineer it from scratch: programming burden, bugs, … What if the network layer tried to provide reliable delivery? End-to-end argument Problem #1) there are applications that require speedy delivery, even if it’s lossy Problem #2) by the way, can the network even achieve reliable global packet delivery? End-to-end argument “If a function can only be correctly implemented end-to-end, it must be implemented in the end systems. Implementing it in the network can, at best, only be an optimization.” Fate-sharing principle To deal with potential failures, store critical system state at the nodes which rely on that state. Only way to lose that state is if the node that relies on it fails, in which case it does not matter. Fate-sharing principle Packet vs. circuit switching Packet switching beats circuit switching with respect to resilience and e ciency ffi Packet vs. circuit switching Which pattern do you think modern video streaming (e.g., Youtube) will follow? Video streaming today Do you know why? Current state of Internet Internet is there for more than 50 years Networks keep growing and more applications are developed TCP/IP is the norm: to program a network application, you simply use the socket APIs So, the network will keep growing with the same set of technologies? Partially, yes! We are still using these old technologies (TCP/IP) But, there are also new developments Innovation in network protocol Innovations in network design Innovations in network design Innovations in network management When ML/RL meets networking Questions?