Admission management of applications with dynamic client-membership and client-level binding in ATM networks
Pratyush Moghé · 1996
Complex applications such as conferencing applications, collaborative work, and client-server applications will soon proliferate in ATM networks. The problem of allocating resources to such applications is a challenging one and one that is not particularly well understood. For instance, it is not enough to just admit these applications using traditional call concepts. New clients might add to an ongoing application, and if new clients are blocked, the service as perceived by the existing clients in the application may degrade. We refer to this as client-level degradation. In this thesis, we explore methods to provide complex applications with a guaranteed bound on client-level degradation. We take two different approaches to the problem. In the first approach, we propose an expanded call definition called enhanced call. The enhanced call encapsulates, in addition to the conventional ATM descriptors and QOS measures, a list of client descriptors and client-level QOS measures. Client descriptors describe the dynamics of how new clients are expected to add to an existing application. Client-level QOS measures quantify the worst-case acceptable client-level degradation. We present an analytical framework that reserves virtual channel links (VCLs) at call setup for future clients. Once the call is set up, we present simple algorithms that check whether arriving clients conform to the client descriptors. Conforming clients can simply be allocated VCLs without an admission process. We discuss viable techniques of dealing with nonconforming clients. In the second approach, we examine the impact of heterogeneity of applications on the perceived degradation. Our objective from the fairness viewpoint is to allocate resources to applications so that the degradation is independent of the type of application. We define a key construct called session that describes the connection resources required by each source client in an application. Two types of sessions are defined--simple and complex. Simple sessions represent point-to-point communication. Complex sessions are used to build complex applications of the type described earlier. We present a link-level admission scheme that uses a threshold to give priority to complex session requests over simple session requests. The threshold is tuned so that simple sessions and complex sessions perceive equal degradation.