The TCP/IP stack has been mainly designed for elastic traffic (file transfers). It is nowadays recognized that it is not able to efficiently support traffic patterns with completely differing requirements (e.g. applications with delay requirements). Service differentiation at the flow agregate level (DiffServ) is a promising way to implement some form of IP QoS because it is robust and scalable. The EDS PHB is a Diffserv PHB based on both loss rate and delay proportional differentiation. In this article, we start from a network layer implementing the EDS service differentiation and present a specific transport protocol that realizes the reliable and interactive transfer of short messages.