Fixing the Internet: Think Locally, Impact Globally Jennifer Rexford Computer Science Department Princeton University

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

Interdomain Routing ASes exchange information with neighbors Destination: block of Internet Protocol addresses AS path: sequence of ASes along the path Local policies in each AS Path selection: which path to use? Path export: which neighbors to tell? “I can reach d via AS 1” “I can reach d” 1 2 3 data traffic data traffic d

Routing Oscillation 1 2 Prefers 1-2-d over 1-d Prefers 2-3-d over 2-d

Business Relationships Provider Peer Peer Customer Customer pays provider Settlement-free peering

Local Control  Global Stability Internet hierarchy No cycles of provider-customer relationships E.g., my customer’s customer is not my provider No free-riding An AS does not support “transit service” for free Peers and providers can only reach the AS’s customers Prefer profitable paths Prefer paths through customers … over paths through peers and providers Guaranteed to converge to unique, stable solution

Interdomain “Route Hijacking” AS 6 owns and announces d AS 1 wrongly announces d 1 2 3 4 5 6 7 d d

Incremental Deployment Complete solution is hard to deploy Address registry, public key infrastructure, cryptography Little benefit to early adopters Incrementally-deployable solutions Individual ASes detect and avoid suspicious paths Maintain history of who announces each destination Prefer paths consistent with path history Significant security gains Small deployments (e.g., top 40 of the 35,000 ASes) Protects around 95% of the Internet Most big ASes learn at least one valid route Most other ASes pick routes chosen by these providers

How to Build Federated Networks Evolvable Technology (under-specified, programmable) ? Autonomy (autonomous parties, with economic/political objectives) Global Properties (stability, scalability, reliability, security, efficiency, managability, …) Can we have all three? Under what conditions?