Application-layer framing

Abstract: This paper is focused on an efficient protocol implementation based on flexible User Protocol Interface (UPI) configurable for different service options and protocol processing architectures. The XTPL implementation discussed in this paper is developed based on the BERKOM eXpress Transfer Protocol (XTP) Lite version for HP 900017x Series using HP-UX 9.0 operating system. This implementation supports the dynamical configuration of user protocol interfaces intended to provide different objectives: - optimization of the user data copy operations (use of the "single copy architecture"); - selectable QoS options for application layer framing, reliability and checksumming. Performance analyses are included to show the flexible use of user protocol interfaces, in particular the reliable single and dual copy interface, dependent on the application traffic of the connections.

Abstract: The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter (xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end user's point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics.

Abstract: In this thesis I try to show that traditional transport protocols (such as TCP) poorly match the requirements of today's applications. Firstly, I develop two new user level protocols using Application Layer Framing (ALF) [20] concepts in order to test this hypothesis. A simple remote login program and a protocol to deliver mailing lists using multicast. In both cases I am able to show that application level protocols utilise less network resources than their traditional counterparts as well as providing improved responsiveness to the user. The development and deployment of new protocols is both difficult and time consuming. I consider a new mechanism for the deployment of protocols. Rather than attempting to deploy them in the end systems, new protocols entities are dynamically deployed into the network. These protocol entities are called proxylets and are written in the programming language Java. A whole infrastructure funnelWeb, [34], has been built to allow the deployment of proxylets. A number of diverse applications are then built around proxylets to show benefits which can be derived from such a scheme. In order to make the funnelWeb infrastructure useful, when globally deployed, a routing infrastructure is designed and partially built.