Towards a versatile transport protocol

n the context of a reconfigurable transport protocol, this paper introduces two protocol instances based on the com- position and specialisation of the TFRC congestion control and Selective Acknowledgment mechanisms. The two result- ing transport architectures lead respectively to the QTP_AF protocol, specifically designed to operate over QoS-enabled networks and the QTP_light protocol, specifically designed for resource-limited end systems connected to powerful servers. QTP_AF combines QoS-aware TFRC congestion control with full reliability to provide a transport service similar to TCP but additionally taking into account network-level band-width reservations. QTP_light proposes a modification of TFRC that shifts from the receiver to the sender the complexity of the loss rate estimation mechanism. This modification allows to alleviate the processing and communication load of "light" resource limited mobile receivers. We present the concept of these protocols and their adaptation in the EuQoS European project framework