On using network tomography for overlay availability

Overlay networks are logical abstraction on a physical network (underlay) where each overlay node corresponds to a specific underlay node and overlay links correspond to paths on the underlay. The use of network layer information for constructing overlay networks can greatly improve their performance. Knowledge of underlay properties such as available bandwidths, loss rates and topology can help in efficient construction, maintenance and optimization of overlays which have to provide service guarantees. In absence of any support from the network core, it becomes necessary to infer those properties by performing end-to-end measurements on the network. We develop probing techniques which infer information about the structure of the underlay and use it for construction of fault-tolerant overlay networks. Algorithms and measurement techniques for the same are presented together with the experimental findings