CSE561 Spring 2001 Venkat Padmanabhan1 CSE561: Graduate Computer Networking Venkat Padmanabhan...

CSE561Spring 2001

Venkat Padmanabhan 1

CSE561: Graduate Computer Networking

Venkat PadmanabhanMicrosoft Research

CSE561Spring 2001


Prelimaries

Instructor: Venkat PadmanabhanEmail: [email protected]: MF, 12:00-1:20 PM, EE1 003Office hours: MF 1:30-2:00 PM, Sieg 226DTA: Andrew WhitakerEmail: [email protected] hours: Th 2:30-3:30 PM, Sieg 433Home page:

http://www.cs.washington.edu/education/courses/561/01sp/

mailto:[email protected]

mailto:[email protected]

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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)

CSE561Spring 2001


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%)

CSE561Spring 2001


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)

CSE561Spring 2001


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

CSE561Spring 2001


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.

CSE561Spring 2001


Mid-term Exam

• Scheduled for Friday, May 11• Focus on understanding rather than

the knowledge of facts

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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)

CSE561Spring 2001


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, …

CSE561Spring 2001


Example – Local Area Network

• Your home network– Ethernet is a broadcast-capable multi-access

LAN

CableModem

PC Laptop

Printer

EthernetHub

CSE561Spring 2001


Example – An Internetwork

• Internetwork is a network of networks• The Internet is a global internetwork in

which all participants speak a common language, IP.

LocalNet 2

LocalNet 1

ISP 2 ISP 1

CSE561Spring 2001


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

CSE561Spring 2001


Growth of the Internet

CSE561Spring 2001


Network Components

Say you want download a file from host A onto host B.

What problems do you need to solve?

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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

CSE561Spring 2001


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)

CSE561Spring 2001


Lecture Roadmap

1. Internet design principles and architecture

2. Medium Access Control3. Internet routing4. Router architectures5. Transport protocols: congestion control6. Transport protocols: interaction with

applications7. Router support for congestion control8. Multicast routing

CSE561Spring 2001


Lecture Roadmap (contd.)

9. Multicast transport and applications10.Naming11.Resource discovery and selection12.Host and network mobility13.Wireless networks (medium access

control)14.Wireless networks (TCP interactions)15.Network and protocol vulnerability16.Active networks

CSE561Spring 2001


Topics Not Covered

• Quality of service• Real-time communication• Traffic measurement and analysis• Ad-hoc networks• … and many others

CSE561Spring 2001


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

CSE561Spring 2001


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

http://www.cs.washington.edu/education/courses/561/01sp/papers/Cla88.pdf

http://www.cs.washington.edu/education/courses/561/01sp/papers/Cla88.pdf

http://www.cs.washington.edu/education/courses/561/01sp/papers/SRC84.pdf

CSE561 Spring 2001 Venkat Padmanabhan1 CSE561: Graduate Computer Networking Venkat Padmanabhan...

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