Improving Internet Availability

1. Improving Internet Availability

2. Some Problems • Misconfiguration • Miscoordination • Efficiency • Market efficiency • Efficiency of end-to-end paths • Scalability • Accountability

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

4. Several “Big” Problems a Week

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

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

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

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

9. Some Problems • Misconfiguration • Miscoordination • Efficiency • Market efficiency • Efficiency of end-to-end paths • Scalability • Accountability

10. Market Inefficiency • Pair of ASes may decide to terminate connectivity arrangement • Even if end nodes would pay for the path to be there! October 2005 April 2007 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 2005 9:50 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 Cogent’s singly homed customers could not reach each other. (~ 4% of the Internet’s prefixes were isolated from each other)

11. Depeerings Continue

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

13. 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

14. 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

15. 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

16. 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