Bandwidth allocation using QoS mapping and a renegotiation scheme for integrated services in MAN-ATM networks.

摘要

Integrated service networks like Asynchronous Transfer Mode (ATM) and Distributed Queue Dual Bus (DQDB) are designed to support various applications. Meeting Quality of Service (QoS) requirements is dependent on the bandwidth allocated to them. Hence, resource sharing becomes a key factor in such an environment. In the case of internetworking between networks, a QoS mapping must be defined in order to meet the requirements of all the applications. In this dissertation, the focus is on the support of real-time applications. For these applications, delay is the most important QoS metric. The delay is estimated for an application and a priority is assigned.; The major contribution of this study is a dynamic bandwidth allocation scheme based on the "Equivalent Capacity", and a renegotiation scheme for applications with dynamic bandwidth requirements. An analytical estimate of the maximum segment delay for Variable Bit Rate (VBR) traffic is derived. The estimated delay, can be used in a delay mapping scheme. A parameter "Sensitivity" is formulated which aids in predicting the bandwidth for real-time traffic sources. In particular, an architecture for DQDB-ATM internetworking, dedicated to the integrated services, is presented. The bandwidth requirement for a station lies in the range ({dollar}BWsb{lcub}min{rcub}, BWsb{lcub}max{rcub}{dollar}). The renegotiation scheme implements a bandwidth reduction algorithm, which can ask a station to reduce its data rate to accommodate more connections or to accept a station's request for more bandwidth. In achieving this, care is taken not to send a station below its negotiated minimum bandwidth.; The second phase of the research involves simulation of the algorithm, and the results of the performance are presented. The maximum segment delay is incorporated into the DQDB stations, in order to simulate the worst possible case. The performance of the renegotiation scheme is studied. The performance of bandwidth allocation scheme with and without the renegotiation is presented. The BONeS DESIGNER is used to simulate the entire network, and verify the algorithm.; To summarize, this dissertation focuses on the following topics: (1) Internetworking connection-oriented DQDB with ATM. (2) Quality of Service mapping. (3) Admission Control. (4) Adaptive bandwidth allocation and renegotiation.