Seminar on “Clean Slate Design for the Internet” Nick McKeown nickm@stanford

1. Seminar on “Clean Slate Design for the Internet”Nick McKeownnickm@stanford.edu

2. High level • “Given what we know today, if we were to start over with a Clean Slate, how would we design a global communications network?” • “Ideally, how will the network look in 15-20 years, and how will we get there from here?”

3. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design

4. Original Architecture • A dumb connectionless packet-forwarding packet-switched infrastructure, with high-level functionality at the edge • Single, simple lowest-common denominator data delivery service (IP), with reliable stream service built on top • Fixed-size numerical addresses with {network, host} hierarchy; one per physical network interface • Later • Separation of IP and TCP (including congestion control using packet loss as congestion signal) • Subnetting, autonomous systems (EGPs and IGPs), DNS, CIDR

5. What is needed • Wouldn’t we like a network that we can trust to be always there, always on, easy to use, universally accessible, secure, and economically viable.  • David Cheriton’s example: If the FAA carried all of its traffic over the public Internet, you'd be nuts to fly. • Some obvious desirable characteristics • Robustness and Availability • Security • Naming and Addressing: accountability vs anonymity • Predictability • Mobility • Economic Viability • What else?

6. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design

7. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design

8. What are others doing? • Background • Incrementalism and “victim of success” of Internet • New era of more radical and fundamental thinking about the future of networks and communications • New-arch (MIT) • 100x100 (CMU) • Geni (NSF/Gov)

9. New-arch (2000) • Requirements for new network • Mobility: Highly dynamic and efficient • Policy-driven auto-configuration • Highly time-variable resources • Allocation of capacity • http://www.isi.edu/newarch/

10. 100x100 (CMU/Stanford/Rice) • NSF Large ITR (2003-2008) • Questions: • Can structure be used to make networks more robust, predictable and manageable? • What economic principles drive the operation of access and backbone networks? • What security primitives must be built into the network? • Can/should network and protocol architectures be designed to take advantage of long-term technology trends? • http://100x100network.org/

11. NSF Geni Initiative (2005) • CISE major effort, seeking congressional funding of approx $300M starting 2008 • Two parts: Research program; Global experimental facility to explore new architectures • Areas of interest: • Creating new core functionality, including naming, addressing, identity, management. • Developing enhanced capabilities: building security intot he architecture; design for high availability; privacy/accountability; design for regional differences and local values • Deploying and validating new architectures • Building higher-level service abstractions • Building new services and applications • Developing new network architecture theories

12. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design

13. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design

14. What we plan to do at Stanford • Weekly Seminar in Fall and Winter • Fall: Talk by professor followed by discussion • Goals • To get thinking about the problem • To learn from each other • To identify some collaborative research projects

15. Prelims • What’s wrong with the Internet…? • Why is the research and business community not already solving it? • What are other groups doing? • What we plan to do at Stanford • An example of “Clean Slate” design How to design backbone networks from a clean slate?

16. Backbone Networks: Emerging Structure • 10-50 routing centers interconnected by long-haul optical links • Increasingly rich topology for robustness and load-balancing • Typical utilization < 25%, because • Uncertainty of traffic matrix network is designed for • Headroom for future growth • Headroom to carry traffic when links and routers fail • Minimize congestion and delay variation • Efficiency sacrificed for robustness and low queueing delay

17. How flexible are networks today? What fraction of allowable traffic matrices can they support? Verio Abilene 25% Over Prov: 0.0004% 50% Over Prov: 1.15% 25% Over Prov: 0.025% 50% Over Prov: 0.66% AT&T Sprint 25% Over Prov: 0.0006% 50% Over Prov: 0.15% 25% Over Prov: 0.0003% 50% Over Prov: 0.06% Verio, AT&T and Sprint topologies are from RocketFuel

18. Desired Characteristics • RobustRecovers quickly; continues to operate under failure • Flexible Will support broad class of applications, new customers, and traffic patterns • PredictableCan predict how it will perform, with and without failures • EfficientDoes not sacrifice cost for robustness

19. Backbone Design • Assume underlying reliable mesh of physical circuits • Dynamic circuit switching over underlying mesh, or • Load-balanced logical network. Describing today

20. Approach • Assume we know/estimate traffic entering and leaving each Regional Network • Requires only local knowledge of users and market estimates • Use Valiant Load Balancing (VLB) over whole network • Enables support of all traffic matrices

21. Valiant Load-Balancing 2r1r2 /rN r2 r1 1 2 3 N rN r3 4 … r4 Capacity provisioned over existing robust mesh of physical circuits

22. A Predictable Backbone Network • Performance: 100% throughput for any valid traffic matrix. • Only need to know aggregate node traffic. • Under low load, no need to spread traffic. • Robustness • Upon failure, spread over working paths • Small cost to recover from k failures: Provision approx 2rirj/r(N-k) • Simple routing algorithm • Efficient • VLB is lowest cost method to support all traffic matrices • Similar cost, while supporting significantly more traffic matrices.

23. How expensive would VLB be? Cost normalized to VLB routing. Cost of switching = cost of transmission for 370miles Verio Abilene 25% Over Prov: 0.0003% Cost: 0.99 50% Over Prov: 1.08% Cost: 1.19 25% Over Prov: 0.026% Cost: 0.87 50% Over Prov: 0.66% Cost: 1.04 AT&T Sprint 25% Over Prov: 0.0004% Cost: 0.94 50% Over Prov: 0.14% Cost: 1.12 25% Over Prov: 0.0002% Cost: 0.86 50% Over Prov: 0.04% Cost: 1.04

24. Open questions • Worst case propagation delay doubled • Low variance in delay • There are “express paths” • (How) are multiple VLB networks connected, and how does performance change? • Economics and policy: how do operators compete?