AGORA: A Market for Internet Connectivity Nick Feamster, Georgia Tech Ramesh Johari, Stanford Vijay Vazirani, Georgia Tech

2 Todays Internet: Bilateral Contracts End-to-end connectivity largely determined by bilateral contracts between pairs of ASes Two types of inefficiency –Market inefficiency: Excess capacity, unfulfilled demand –Connectivity inefficiency: longer-than-necessary paths Comcast Abilene AT&T Cogent $$

3 Market Inefficiency Pair of ASes may decide to terminate connectivity arrangement –Even if end nodes would pay for the path to be there! 31 Jul 2005: Level 3 Notifies Cogent of intent to disconnect. 16 Aug 2005: Cogent begins massive sales effort and mentions a 15 Sept. expected depeering date. 31 Aug 2005: Level 3 Notifies Cogent again of intent to disconnect (according to Level 3) 5 Oct :50 UTC: Level 3 disconnects Cogent. Mass hysteria ensues up to, and including policymakers in Washington, D.C. 7 Oct 2005: Level 3 reconnects Cogent During the outage, Level 3 and Cogents singly homed customers could not reach each other. (~ 4% of the Internets prefixes were isolated from each other) October 2005April 2007

4 Connectivity Inefficiency Paths become longer simply because two ASes decide not to interconnect Comcast Abilene AT&T Cogent $$ Peering points in Atlanta Peering point in Washington, D.C.

5 AGORA: AGregator-Oriented Architecture End-to-end paths flow through aggregators Long-haul providers offer connectivity between aggregators Connectivity between aggregators is black-box –May be connectivity on single path, or along multiple paths Structure of Internet paths Exploit new structure to allow new types of contracts Two Proposed Changes Aggregators as waypoints (layer 3 exchanges) Market makers as clearinghouses M

6 Protocol Operation Provider advertises, per ingress/egress pair –available capacity and –a price for that capacity Market maker(s) compile the pairs of endpoints to be bought and sold Stub networks request end-to-end connectivity from market makers Market makers solve an optimization problem and allocate resources to stub networks

7 Contracts: Three Types Best effort connectivity Long-term contracts –Established ahead of time, for set of destinations that stub network is really concerned with reaching Short-term contracts –Recovery from rare, catastrophic periods of disconnection

8 Challenges Protocol for resource advertisement –PCE/Interdomain connectivity database (?) Algorithm for resource allocation and computation of end-to-end paths Protocol to handle transactions for resources –Possible race conditions Scaling considerations Incentives for long-haul providers to invest