Lowering the Barriers to Innovation

1
Lowering the Barriers to Innovation

• Jennifer Rexford
• Computer Science Department
• Princeton University
• http//www.cs.princeton.edu/jrex

2
Flash Back to 1984
3
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 ATT Labs
• Designing the future Internet
• Research and teaching with undergraduate and
  graduate students at Princeton

4
How the Internet Enables Innovation
5
Innovative Applications
Tim Berners-Lee CERN Researcher World Wide Web
iPhone apps
6
Innovative Communication Media
Cable
Satellite
Cellular
Ethernet
DSL
Bluetooth
WiFi
Fiber optics
7
Telephone Network
Smart Network
Dumb Terminals
8
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

9
Internet
Dumb Network
Smart Terminals
10
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.
11
What Does the Dumb Network Do?

• Best-Effort Packet Delivery

12
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

• Whats in an IP packet?
• The data you want to send
• A header with the from and to addresses

13
Why Packets?

• Data traffic is bursty
• Logging in to remote machines
• Exchanging e-mail messages
• Dont waste bandwidth
• No traffic exchanged during idle periods
• Better to allow sharing of resources
• Different transfers share access to same links

14
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
15
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.
16
Power to the Users Computer
Run neat applications!
Operating System

• Overcome network limitations
• Retransmit lost or corrupted packets
• Put the received data back in order
• Slow down under congestion

packets
17
The Result Tremendous Innovation
Internet Protocol
18
So, Whats the Problem?

• (And where do I come in?)

19
Misplaced Trust in the End Host

• Security vulnerabilities
• No strict notions of identity
• Powerful computers
• Many attacks
• Denial of service
• Spam e-mail
• Phishing
• Identity theft
• How do we protectthe Internet?

20
Nobody is In Charge
Around 50,000 independent networks
4
3
5
2
6
7
1
Web server
Client
How to manage a global federated network?
21
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

22
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! ?

23
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!

24
Thanks!

• (Any Questions?)