Wednesday, January 19, 2011

Thoughts on RON: Resilient Overlay Networks

Authors: David G. Andersen, Hari Balakrishnan, M. Frans Kaashoek, Robert Morris

Venue: Proc. 18th ACM SOSP, Banff, Canada, October 2001


The paper describes the design and implementation of an overlay network that can be used to subvert the underlying default IP routing. A RON is a set of nodes that cooperate to select the best overlay path to route traffic over given an application's requirements. The application links to the RON library and uses the library's functions to send and receive traffic. Each RON node monitors the connection quality to every other node in the network, and uses that information to best route traffic.

There is no authentication in RON, and all nodes have to implicitly trust each other. However, RON does provide the ability for node providers to specify complex policies on what traffic to accept (constrained by the lack of authentication). But without authentication, it would be difficult to bill any particular entity for traffic, an important aspect given that RON nodes need to be quite powerful.

Apparently, a route diversion of only one hop has been found to achieve quite a significant boost in performance and to solve most of the problems, and it was found that routing over RON has enabled connectivity recovery in less than 20s, much faster than BGP reconvergence.

RON does not scale well, and so RONs need to be limited in size to about 50. The scalability bottleneck is due to the fact that each node does quite a bit of monitoring on various paths and maintains a large database. However, there have been follow ups to the work that try to improve on the scalability.

No comments:

Post a Comment