Rethinking end-to-end failover with transport layer multihoming

Using the application of bulk data transfer we investigate end-to-end failover mechanisms and thresholds for transport protocols that support multihoming (e.g., SCTP). First, we evaluate temporary failovers, and measure the tradeoff between aggressive (i.e., lower) thresholds and spurious failovers. We surprisingly find that spurious failovers do not degrade performance, and often actually improve goodput regardless of the paths' characteristics (bandwidth, delay, and loss rate). A permanent failover mechanism tries to avoid throttling the sending rate by not returning to a primary path when it recovers. We demonstrate that such a mechanism can be beneficial if the sender can estimate each path's RTT and loss rate. We advocate a new approach to end-to-end failover that temporarily redirects traffic to all alternate path on the first sign of a potential failure (i.e., a timeout) on the primary path, but conservatively proceeds with failure detection of the primary path in the background.