Lowering the Barriers to Innovation Jennifer Rexford Computer Science Department Princeton University

Flash Back to 1984

Fast Forward to Today How computers work –Electrical engineering degree at Princeton Making multiple computers work together –Parallel computing research at U. Michigan Interconnecting computers via the Internet –Research at AT&T Labs Designing the future Internet –Research and teaching with undergraduate and graduate students at Princeton

How the Internet Enables Innovation

Innovative Applications Shawn Fanning Northeastern freshman Napster Tim Berners-Lee CERN Researcher World Wide Web Meg Whitman E-Bay iPhone apps

Innovative Communication Media Ethernet Fiber optics Cable DSL WiFi Cellular Satellite Bluetooth

Telephone Network Smart Network Dumb Terminals

Plain Old Telephone Service (POTS) Dumb phones –Dial a number –Speak and listen Smart switches –Set up and tear down a circuit –Forward audio along the path Limited services –Audio –Later, fax, caller-id, … A monopoly for a long time

Internet Dumb Network Smart Terminals

Power at the Edge End-to-End Principle Whenever possible, communications operations should occur at the end-points of a system. Programmability With programmable end hosts, new network services can be added at any time, by anyone. And then computers became powerful and ubiquitous….

What Does the “Dumb” Network Do? Best-Effort Packet Delivery

Internet Protocol (IP) Packet Switching Much like the postal system –Divide information into letters –Stick them in envelopes –Deliver them independently –And sometimes they get there What’s in an IP packet? –The data you want to send –A header with the “from” and “to” addresses

Why Packets? Data traffic is bursty –Logging in to remote machines –Exchanging messages Don’t waste bandwidth –No traffic exchanged during idle periods Better to allow sharing of resources –Different transfers share access to same links

Why Best Effort? Best-effort delivery –Packets may be lost, corrupted, delayed, or delivered out-of order Keeps the network simple –No retransmission, error correction, or guarantees of packet delivery, … source destination IP network

Supporting Diverse Link Technologies Best-effort packet delivery over most anything –Serial link, fiber optic link, coaxial cable, wireless Even birds –IP Datagrams over Avian Carriers IP over Avian Carriers was actually implemented, sending 9 packets over a distance of approximately 3 miles, each carried by an individual pigeon, and they received 4 responses, with a packet loss ratio of 55%, and a response time ranging from 3000 seconds to over 6000 seconds.

Power to the User’s Computer Operating System packets Overcome network limitations –Retransmit lost or corrupted packets –Put the received data back in order –Slow down under congestion Run neat applications!

The Result: Tremendous Innovation Internet Protocol

So, What’s the Problem? (And where do I come in?)

Misplaced Trust in the End Host Security vulnerabilities –No strict notions of identity –Powerful computers Many attacks –Denial of service –Spam –Phishing –Identity theft How do we protect the Internet?

Nobody is In Charge Client Web server Around 50,000 independent networks How to manage a global federated network?

Hard to Change the Inside of the Internet Internet infrastructure –Scalability –Stability –Reliability –Performance –Energy-efficiency –Security Internet Protocol Can we make the inside programmable? –To unleash a wave of innovation

My Research Challenge A future Internet worthy of our trust –More secure, scalable, stable, reliable, efficient, … –More flexible and evolvable over time Despite all the challenges –Greedy and malicious users –Networks driven by economics and politics Without losing all the good stuff –Innovative applications –Innovative communication media I think this will keep me busy for awhile!

What I Love About My Job Learn new stuff all the time Pick the research problems I work on Pick the people I want to work with Have real impact on the world today And (hopefully) bigger impact in the future While wearing jeans to work every day!

Thanks! (Any Questions?)