1. Mutually Controlled Routing with Independent ISPs Offense Gary Bramwell Zhaosheng Zhu

2. 2 Good for every ISP? r They say in nearly every case it brings benefit for every ISPs.  Admits that some ISPs lose “The graph shows that a handful of ISPs do lose a little. These are small, edge ISPs for whom the changed routing pattern represents a minor loss according to our measure.” r What is a “minor loss”? r It makes path selection sensitive to the concerns of both ISPs. But why is this win-win? No proof

3. 3 Is it stable r One link cost change will cost time to converge r Link costs change with traffic m Delay and congestion never constant m Recalculation will be frequent and expensive

4. 4 Why Global?  How to define a global optimization? Someone prefer minimal path length while someone prefer minimal loss rate.  What is the goal of global optimization?  Should ISPs care about this?  ISPs care about local optimization over global

5. 5 Implementation Issues r Using one router to re-normalize costs m Drastically increases convergence time m Other routers behave as if changes don’t occur until calculation is complete m Lowering priority of the calculation enhances these issues m Single point of failure

6. 6 Win-Win? r Claims that Wiser is win-win for everyone m Some ISPs still have a loss m No motivation to implement protocol r Counterclaim - re-negotiate normalizations for ISPs who lose m Increases complexity for ISPs over current BGP agreements r What is ‘Gain’? m Not clearly defined

7. 7 Cheating r Harder to detect cheating vs. BGP m BGP just considers reachability, but Wiser allows costs to be cheated as well m Harder to determine, as ISPs rely on data from one another to determine costs m Several ISPs working together to cheat not tested

8. 8 Cheating r Pair of ISPs studied, % of ISPs cheating makes no sense

9. 9 Convergence r Convergence takes far longer for Wiser than BGP m Several orders of magnitude worse m Unacceptable for QoS

10. 10 Convergence

11. 11 Conclusion r Wiser still creates a loss for some ISPs r Stability issues still need to be addressed m Convergence time m Points of failure for calculating changes r Cheating must be investigated more r Not enough motivation for ISPs to adopt m Benefits not clearly defined