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Can Economic Incentives Make the ‘Net Work?

Can Economic Incentives Make the ‘Net Work?. Jennifer Rexford Princeton University http://www.cs.princeton.edu/~jrex. What is an Internet?. A “network of networks” Networks run by different institutions Autonomous System (AS) Collection of routers run by a single institution

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Can Economic Incentives Make the ‘Net Work?

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  1. Can Economic Incentives Make the ‘Net Work? Jennifer RexfordPrinceton University http://www.cs.princeton.edu/~jrex

  2. What is an Internet? • A “network of networks” • Networks run by different institutions • Autonomous System (AS) • Collection of routers run by a single institution • ASes have their own local goals • E.g., different views of which paths are good • Interdomain routing reconciles those views • Computes end-to-end paths through the Internet Wonderful problem setting for game theory and mechanism design

  3. Three Parts to This Talk • Today’s interdomain routing • Protocol allows global oscillation to occur • Yet, rational behavior ensures global stability • Improving today’s interdomain routing • Today’s routing system is not flexible enough • Allow greater flexibility while ensuring stability • Rethinking the Internet routing architecture • Refactoring the business relationships entirely • Raising a host of new open questions…

  4. Autonomous Systems (ASes) Path: 6, 5, 4, 3, 2, 1 4 3 5 2 6 7 1 Web server Client Around 35,000 ASes today…

  5. Border Gateway Protocol (BGP) • ASes exchange reachability information • Destination: block of IP addresses • AS path: sequence of ASes along the path • Policies “programmed” by network operators • Path selection: which path to use? • Path export: which neighbors to tell? “I can reach d via AS 1” “I can reach d” 2 3 1 data traffic data traffic d

  6. 2 3 d 2 d 2 1 2 d 1 d d 1 3 1 d 3 d 3 Stable Paths Problem (SPP) Model • Model of routing policy • Each AS has a ranking of the permissible paths • Model of path selection • Pick the highest-ranked path consistent with neighbors • Flexibility is not free • Global system may not converge to a stable assignment • Depending on the way the ASes rank their paths

  7. Better choice! Only choice! Top choice! Better choice! Only choice! Only choice! Policy Conflicts  Convergence Problems 1 2 0 1 0 1 0 3 1 0 3 0 2 3 0 2 0 3 2 In the meantime, data traffic is going every which way…

  8. Ways to Achieve Global Stability • Detect conflicting rankings of paths? • Computationally intractable (NP-hard) • Requires global coordination • Restrict the policy configuration languages? • In what way? How to require this globally? • What if the world should change, and the protocol can’t? • Rely on economic incentives? • Policies typically driven by business relationships • E.g., customer-provider and peer-peer relationships • Sufficient conditions to guarantee unique, stable solution

  9. Bilateral Business Relationships • Provider-Customer • Customer pays provider for access to the Internet • Peer-Peer • Peers carry traffic between their respective customers 1 Valid paths: “6 4 3 d” and “8 5 d” Invalid paths: “6 5 d” and “1 4 3 d” Valid paths: “1 2 d” and “7 d” Invalid path: “5 8 d” 4 3 2 d 5 6 Provider-Customer 7 Peer-Peer 8

  10. Act Locally, Prove Globally • Global topology • Provider-customer relationship graph is acyclic • Peer-peer relationships between any pairs of ASes • Route export • Do not export routes learned from a peer or provider • … to another peer or provider • Route selection • Prefer routes through customers • … over routes through peers and providers • Guaranteed to converge to unique, stable solution

  11. Rough Sketch of the Proof • Two phases • Walking up the customer-provider hierarchy • Walking down the provider-customer hierarchy 1 4 3 2 d 5 6 Provider-Customer 7 Peer-Peer 8

  12. Trade-offs Between Assumptions • Three kinds of assumptions • Route export, route selection, global topology • Relax one, must tighten the other two • Are these assumptions reasonable? • Could business practices change over time? • Two unappealing features • An AS picks a single best route • An AS must prefer routes through customers

  13. A Case For Customized Route Selection • ISPs usually have multiple paths to the destination • Different paths have different properties • Different neighbors may prefer different routes Shortest latency Most secure Bank VoIP provider School Lowest cost 13

  14. Neighbor-Specific Route Selection • A node has a ranking function per neighbor is node i’s ranking function for neighbor node j. 14

  15. Stability Conditions for NS-BGP • Surprisingly, NS-BGP improves stability! • Neighbor-specific selection is more flexible • Yet, requires less restrictive stability conditions • “Prefer customer” assumption is not needed • Choose any “permissible” route per neighbor • That is, need just two assumptions • No cycle of provider-customer relationships • An AS does not export routes learned from one peer or provider to other peers or providers

  16. Why Do Weaker Conditions Work? 1 2 0 1 0 • An AS always tells its neighbor a route • If it has any route that is permissible for that neighbor 1 0 3 1 0 3 0 2 3 0 2 0 3 2

  17. Customized Route Selection • Customized route selection as a service • Select a different best route for different neighbors • Different menu options • Cheapest route (e.g., “prefer customer”) • Best performing routes • Routes that avoid undesirable ASes (e.g., censorship) • Nice practical features of NS-BGP • An individual AS can deploy NS-BGP alone • … and immediately gain economic value • Without compromising global stability!

  18. Tomorrow’s Internet Hosting “virtual networks” over infrastructure owned by many parties Looking Forward: “Cloud Networking” • In Today’s Internet Competing ASes with different goals must coordinate • Infrastructure providers: Own routers, links, data centers • Service providers:Offer end-to-end services to users Economics play out vertically on a coarser timescale.

  19. Advantages of Virtual Networks • Simplifies deployment of new technologies • Easier to deploy in a single (virtual) network • Multicast, quality-of-service, security, IPv6, … • Enables the use of customized protocols • Secure addressing & routing for online banking • Anonymity for Web browsing • Low delay for VoIP and gaming • Greater accountability • Direct relationship with infrastructure providers • Account for performance/reliability of virtual links

  20. Conclusions • Internet is a network of networks • Tens of thousands of Autonomous Systems (ASes) • Network protocols are very flexible • To enable autonomy and extensibility • Global properties are not necessary ensured • Stability, efficiency, reliability, security, managability, … • Economic incentives sometimes save the day • E.g., rational local choices ensure global stability • Are we willing to rely on economic motivations? • Do we have any choice?

  21. References Related to This Talk • “The stable paths problem and interdomain routing” • Tim Griffin, Bruce Shepherd, and Gordon Wilfong • http://portal.acm.org/citation.cfm?id=508332 • “Stable Internet routing without global coordination” • Lixin Gao and Jennifer Rexford • http://www.cs.princeton.edu/~jrex/papers/sigmetrics00.long.pdf • "Neighbor-Specific BGP: More flexible routing policies while improving global stability“ • Yi Wang, Michael Schapira, and Jennifer Rexford • http://www.cs.princeton.edu/~jrex/papers/nsbgp_sigmetrics09.pdf • "How to lease the Internet in your spare time" • Nick Feamster, Lixin Gao, and Jennifer Rexford • http://www.cs.princeton.edu/~jrex/papers/cabo-short.pdf

  22. Other Related Research Papers • Inherently Safe Backup Routing with BGP • http://www.cs.princeton.edu/~jrex/papers/infocom01.pdf • Design Principles of Policy Languages for Path Vector Protocols • http://conferences.sigcomm.org/sigcomm/2003/papers/p61-griffin.pdf • Implications of Autonomy for the Expressiveness of Policy Routing • http://conferences.sigcomm.org/sigcomm/2005/paper-FeaBal.pdf • Metarouting • http://conferences.sigcomm.org/sigcomm/2005/paper-GriSob.pdf • An Algebraic Theory of Interdomain Routing • http://portal.acm.org/citation.cfm?id=1103561 • Searching for Stability In Interdomain Routing • http://www.cs.yale.edu/homes/schapira/PID808559.pdf

  23. Related Papers With Game Theory • Interdomain Routing and Games • http://www.cs.huji.ac.il/~mikesch/routing_games-full.pdf • Rationality and Traffic Attraction: Incentives for Honest Path Announcements in BGP • http://ccr.sigcomm.org/online/?q=node/395 • Incentive-Compatible Interdomain Routing • http://cs-www.cs.yale.edu/homes/jf/FRS.pdf • Mechanism Design for Policy Routing • http://cs-www.cs.yale.edu/homes/jf/FSS.pdf • The Complexity of Game Dynamics: BGP Oscillations, Sink Equlibria, and Beyond • http://www.cs.berkeley.edu/~alexf/papers/fp08.pdf • Specification Faithfulness in Networks with Rational Nodes • http://www.eecs.harvard.edu/econcs/pubs/podc04.pdf • Distributed Algorithmic Mechanism Design • http://cs-www.cs.yale.edu/homes/jf/AGTchapter14.pdf • Partially Optimal Routing • http://www.stanford.edu/~rjohari/pubs/por.pdf

  24. Background on Interdomain Economics • http://drpeering.net/a/Home.html • http://www.fcc.gov/Bureaus/OPP/working_papers/oppwp32.pdf • http://www.potaroo.net/papers/1999-6-peer/peering.pdf • http://www.cisco.com/en/US/about/ac123/ac147/ac174/ac201/about_cisco_ipj_archive_article09186a00800c83a5.html • http://www.cisco.com/en/US/about/ac123/ac147/ac174/ac200/about_cisco_ipj_archive_article09186a00800c8900.html • http://www.vjolt.net/vol3/issue/vol3_art8.html

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