CSE561: Graduate Computer Networking

CSE561: Graduate Computer Networking Venkat Padmanabhan Microsoft Research Venkat Padmanabhan

Prelimaries Instructor: Venkat Padmanabhan Email: padmanab@cs.washington.edu Lectures: MF, 12:00-1:20 PM, EE1 003 Office hours: MF 1:30-2:00 PM, Sieg 226D TA: Andrew Whitaker Email: andrew@cs.washington.edu Office hours: Th 2:30-3:30 PM, Sieg 433 Home page: http://www.cs.washington.edu/education/courses/561/01sp/ Venkat Padmanabhan

What’s this class about? • Reading 25-30 papers spanning a wide spectrum of the networking research literature • Learning how to critique networking research • Learning how to do networking research through a hands-on project Venkat Padmanabhan

Am I ready to take this class? • If you have taken CSE 461 or an equivalent undergraduate class elsewhere, then you’re all set. • If you haven’t but have at least some background in computer systems, you can read through a basic textbook (e.g., the book by Peterson & Davie) without much effort. • Minimal coverage of basic material in class Venkat Padmanabhan

Syllabus Focus on the Internet-related research • Design philosophy and architecture • Medium access control (Ethernet, wireless) • Routing (BGP) • Transport (TCP) • Applications (Web/HTTP, audio/video) • Novel paradigms (multicast, active networks) • Novel networks (wireless, mobile) • Security (protocol vulnerability, DoS attacks) Venkat Padmanabhan

What you are expected to do • Read and review research papers (20%) • Actively participate in discussions in class and on the mailing list (10%) • Take midterm exam (20%) • Define and work on a networking research project (50%) Venkat Padmanabhan

Literature Review • 25-30 research papers • all available online on the course home page • only need to review papers marked as such • “optional reading” need not be reviewed • Review (one page max per paper) • summarize paper in just a few sentences • highlight contributions/lessons learned • point out shortcomings in assumptions, approach, data, etc. (ignore presentation problems!) • bonus points for comparing and contrasting with related literature (from reading list or elsewhere) Venkat Padmanabhan

Literature Review (contd.) • Reviews • OK to discuss papers with others at any time • But you must write your own review! • Hardcopy due at the start of each lecture • You may choose to post your review on the mailing list after the lecture period to get some discussion going Venkat Padmanabhan

Class Participation • Read the papers before coming to class • Actively participate in discussion in class and on the mailing list • Remember: there are few absolute truths in networking. So don’t be afraid to be a contrarian. Venkat Padmanabhan

Mid-term Exam • Scheduled for Friday, May 11 • Focus on understanding rather than the knowledge of facts Venkat Padmanabhan

Project • Define and work on a research project that • is interesting • explores novel issues or approaches • is doable in the available time • Groups of 2-3 students (not a rule) • You are encouraged to come up with ideas • feel free to brainstorm on ideas with others • aim high! The best projects could lead to papers at the top conferences (SIGCOMM,Infocom,Mobicom) • I’ll distribute a list of potential projects in class next week Venkat Padmanabhan

Project (contd.) • Project scope • implementation, simulation, measurement, analysis, or some combination thereof • this is not about doing a literature survey • The process • initial meeting (April 6) • 1-2 page project proposal due April 13 • problem statement, specific goals, resources you need, plan of attack, (anticipated) deliverables • not a rigid document Venkat Padmanabhan

Project (contd.) • The process (contd.) • checkpoint meetings after class on May 7 • project presentations and final report due the first week of June (exact date TBD) Venkat Padmanabhan

Elements of a Network • Links carry information (bits) • Wire, wireless, fiber optic, smoke signals … • Switches move bits between links • Routers, gateways, bridges, CATV headend, PABXs, … • Hosts are the communication endpoints • PC, PDA, cell phone, toaster, … Venkat Padmanabhan

Example – Local Area Network Ethernet Hub • Your home network • Ethernet is a broadcast-capable multi-access LAN Cable Modem Printer Laptop PC Venkat Padmanabhan

Example – An Internetwork • Internetwork is a network of networks • The Internet is a global internetwork in which all participants speak a common language, IP. ISP 2 ISP 1 Local Net 1 Local Net 2 Venkat Padmanabhan

Key Features of the Internet • Distributed • decentralized operation, global reach • Large-scale • 110 million hosts (Jan 2001) and growing • Heterogeneous • links, end-points • Intelligent end-points • supercomputers, PCs, PDAs • Multi-purpose • Web, audio/video conferencing, telnet Venkat Padmanabhan

Growth of the Internet Venkat Padmanabhan

Network Components Say you want download a file from host A onto host B. What problems do you need to solve? Venkat Padmanabhan

Host Discovery Locating the remote host • The “naming” problem • provides a level of indirection between names and addresses • Domain Name System (DNS) • the “telephone directory” of the Internet Venkat Padmanabhan

Medium Access Control Putting bits on the wire • The network carries packets, not bits • framing to create packets out of bits • Physical medium may be shared • example: Ethernet, wireless • medium access control (MAC) to arbitrate amongst several contenders • Actually, the network only carries electrical or optical signals • modulation to convert digital data into analog signals Venkat Padmanabhan

Routing How do a packet find its way through the network? • Internet is distributed • no central “brain” • routing happens in a decentralized manner • Internet is not owned by any one organization • hierarchical routing architecture • intra-domain and inter-domain Venkat Padmanabhan

Transport Protocol How do you ensure reliable transmission of the file over an unreliable network? • Links and routers are a shared resource • a packet may be dropped when the resource is over-utilized (or even otherwise!) • resources need to be apportioned “fairly” • Need to perform loss recovery and congestion control • Transmission Control Protocol (TCP) • responsible the vast majority of Internet traffic Venkat Padmanabhan

Interaction of Transport Protocols with Applications One size doesn’t fit all • Transfer size • a protocol designed for large file transfers may be too heavyweight for exchanging short messages • Reliability • necessary for ordinary file transfer • not necessary for live streaming audio Venkat Padmanabhan

Multicast Several clients may want to download a file at the same time • Repeated unicast would be inefficient • Need to multicast the file • avoid sending a packet over a link repeatedly • Multicast makes existing problems harder, especially because of heterogeneity • routing • loss recovery • congestion control Venkat Padmanabhan

Resource Discovery Say you have a choice of where to download the file from • Best to download it from “nearest” source • this is exactly the goal of content distribution networks (e.g., Akamai) • But Internet “distance” is not a static metric and is hard to measure Venkat Padmanabhan

Security It ain’t a friendly world out there! • Eavesdropping on conversations • Masquerading as another entity • man-in-the-middle attack • Non-compliance with the protocols • Deliberate overconsumption of resources • denial of service attack Venkat Padmanabhan

Mobility Hosts and/or networks may be mobile • Examples: • a person carrying a laptop from work to home • a planeload of people • Maintaining Internet connectivity in the face of mobility • mobility impacts most of the other components (discovery, routing, transport, applications, security) Venkat Padmanabhan

Lecture Roadmap • Internet design principles and architecture • Medium Access Control • Internet routing • Router architectures • Transport protocols: congestion control • Transport protocols: interaction with applications • Router support for congestion control • Multicast routing Venkat Padmanabhan

Lecture Roadmap (contd.) • Multicast transport and applications • Naming • Resource discovery and selection • Host and network mobility • Wireless networks (medium access control) • Wireless networks (TCP interactions) • Network and protocol vulnerability • Active networks Venkat Padmanabhan

Topics Not Covered • Quality of service • Real-time communication • Traffic measurement and analysis • Ad-hoc networks • … and many others Venkat Padmanabhan

Next Lecture: Internet Design Principles and Architecture • History and evolution of the Internet • Current architecture • Defining principles: • layering • datagram service • statistical multiplexing • decentralized architecture • end-to-end principle Venkat Padmanabhan

Next Lecture (contd.) • Papers to read • D. Clark, The Design Philosophy of the DARPA Internet Protocols, ACM SIGCOMM 1988 • .H. Saltzer, D.P. Reed, D.D. Clark, End-to-End Arguments in System Design, ACM TOCS, November 1984 • The optional papers are also classics! • No reviews due Venkat Padmanabhan

CSE561: Graduate Computer Networking