Measurement Techniques in On-Demand Overlays for Reliable Enterprise IP Telephony

Maintaining good quality of service for real-time applications like IP Telephony requires quick detection and reaction to network impairments. In this paper, we propose and study novel measurement techniques in ORBIT, which is a simple, easily deployable architecture that uses single-hop overlays implemented with intelligent endpoints and independent relays. The measurement techniques provide rapid detection and recovery of IP Telephony during periods of network trouble. We study our techniques via detailed simulations of several multi-site enterprise topologies of varying sizes and three typical fault models. We show that our proposed techniques can detect network impairments rapidly and rescue IP Telephony calls in sub-second intervals. We observed that all impacted calls were rescued with only a few relays in the network and the run-time overhead was low. Furthermore, the relay sites needed to be provisioned with minimal additional bandwidth to support the redirected calls.