Improving Internet Availability

Some Problems Misconfiguration Miscoordination Efficiency –Market efficiency –Efficiency of end-to-end paths Scalability Accountability

Two Philosophies Bandage: Accept the Internet as is. Devise band-aids. Amputation: Redesign Internet routing to guarantee safety, route validity, and path visibility

Several Big Problems a Week

Goal: Proactive Fault Detection Idea: Analyze configuration before deployment Configure Detect Faults Deploy rcc Many faults can be detected with static analysis. Feamster et al., Detecting BGP Configuration Faults with Static Configuration Analysis, NSDI, May 2005

rcc rcc Overview Normalized Representation Correctness Specification Constraints Faults Analyzing complex, distributed configuration Defining a correctness specification Mapping specification to constraints Challenges Distributed router configurations (Single AS)

Summary: Faults across 17 ASes Route ValidityPath Visibility Every AS had faults, regardless of network size Most faults can be attributed to distributed configuration

Routing Control Platform iBGP RCP After: RCP gets best iBGP routes (and IGP topology) iBGP eBGP Before: conventional iBGP Caesar et al., Design and Implementation of a Routing Control Platform, NSDI, 2005

Some Problems Misconfiguration Miscoordination Efficiency –Market efficiency –Efficiency of end-to-end paths Scalability Accountability

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

Depeerings Continue

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

Idea Separate path setup from maintenance of connectivity on individual networks –Enable customers who value end-to-end paths to actually pay for those paths Establish a market for the exchange of segments –Interdomain RCP facilitates this market

MINT: Market for Internet Transit New types of contracts –ISPs advertise path segments –Edge networks bid for end-to-end paths –Mediator assembles segments into paths Exchanges as waypoints between segments Mediator collects information about path segments and sells end- to-end paths to edge networks M

Protocol Operation Provider advertises, per ingress/egress pair –Segment properties –A price for that segment Mediator(s) compile the pairs of endpoints to be bought and sold Edge networks request end-to-end connectivity Mediators solve an optimization problem and allocate resources to edge networks

Questions Contract setup –Protocols for tracking available capacity of segments –Scalability of mediator architecture –Efficiency of resulting contracts Contract enforcement –How can edge networks determine that they are receiving a certain level of service? Performance under churn –Containing churn within an ISP when links fail –Limiting recomputation of end-to-end paths