We report our project aimed at the design and implementation of a mid-ware tool kit, called NetEx, that provides deadline-guaranteed and connectionoriented communication services at the application layer. NetEx comprises of a Host Traffic Manager (HTM) and a Network Traffic Manager (NTM). An HTM resides in each participating host while the NTM can be implemented either at a central host or in a distributed manner. The HTM performs traffic scheduling and enforces traffic regulation at individual hosts. The NTM is the decision maker on connection admission control. We argue that portability and efficiency are two fundamental issues one has to address in the design of such a middleware tool kit. We present strategies adopted by NetEx in order to support portability and efficiency. We report system performance based on several benchmarks.
In this paper, we report our work on adaptive connection admission control in real-time communication networks. Much of the existing work on connection admission control (CAC) specifies the QoS parameters as fixed values and does not exploit the dynamic fluctuations in resource availability. We take an innovative approach: First, we allow an application to specify QoS in a range, rather than fixed values. Second and more importantly, we design, analyze, and implement CAC modules that, based on QoS specified over a range, adaptively allocate system resources to connections. Delay analysis is an integral part of connection admission control. Our adaptive CAC uses an efficient delay analysis method to derive a closed form solution for endto-end delay of messages in a connection. With our adaptive CAC, we demonstrate an improvement in the system performance in terms of the probability of admitting connections and the QoS offered to the payload connections.
This paper focuses on connection management for mission critical real-time applications over ATM networks. Traditional connection management generally requires Quality-of-Service (QoS) parameters to be specified as fixed values, and can only provide a QoS that is constant throughout the lifetime of an admitted connection. Such simplistic specification and consequent resource management offer no flexibility to user applications. The applications cannot receive the best possible QoS, and system resources are grossly under-utilized We take an adaptive approach. With our adaptive connection management, QoS of connections is specified over a range of values. Resources are reallocated and redistributed in response to dynamic fluctuations in resource availability. With our adaptive strategy, we demonstrate dramatic improvements in both the offered QoS to applications, and the effective utilization of system resources. Our approach is practical and compatible with current networking standards. We have implemented adaptive connection management in a newer version of our real-time toolkit, Ne& NetEx provides delay guaranteed communication services for mission critical real-time applications over high-speed networks.
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