Colin James Parris

Dynamic rerouting of guaranteed Quality-of-Service connections

To support the widespread demands for integrated services various solutions have been proposed to provide guaranteed Quality-of-Service (QoS) services in packetswitched networks. These solutions usually require fixed route selection and resource reservation on a per connection basis. The routing and reservation decisions, combined with load fluctuations, introduce the problems of network unavailability and loss of network management flexibility. We believe that these problems can be alleviated by transparently rerouting connections to properly balance the network load. In this paper, we present a solution that supportstransparent route modification ofguaranteed QoS connections during the life time of the connections. As the emphasis of this work is to support transparency we must ensure that during and after the rerouting, the QoS guarantees made to the client are preserved, and the interface instances at both the sender and receiver are unaltered. Our solution includes the mechanisms that support the transparent rerouting of connections, and a routing algorithm that is based on the traffic characteristics, the delay, and the jitter requirements of a connection. This routing algorithm can also use various administrative constraints and facilitate the reuse of resources currently reserved by the connection. To optimize the solution, additional mechanisms have been introduced to reduce the time needed to reroute a connection and to support rerouting of segments of a connection. The solution has been implemented in the context of the Tenet scheme and route changes can be observed and controlled by using the Simple Network Management Protocol (SNMPv 1). Simulation experiments and some initial measurements of the implementation demonstrate that such a scheme is useful, practical, and can be achieved with load overhead.

Research: The implementation of a dynamic management scheme for guaranteed-performance connections

In this paper we present a prototype implementation of a management scheme that can be used to dynamically manage Guaranteed Performance Connection (GPC) services in Integrated Services Networks. These services are required to support the wide range of quality-of-service parameters desired by many useful applications. The GPC services provide performance guarantees in terms of throughput, delay, delay jitter and loss rates, and adopt a connection-oriented, fixed-route, reservation-oriented approach to achieve these guarantees. In such an approach, resource allocation and route selection decisions are usually static (i.e. they are made before the start of the communication on the basis of resource availability and real-time network load at that time, and are usually kept for the duration of the communication). This static approach limits the flexibility of these GPC services. In our previous work we presented our solution to this lack of flexibility. This solution, the Dynamic Connection Management (DCM) Scheme, provides the network with the capability to dynamically modify the traffic characteristics, the performance requirements, and the route of any existing guaranteed-performance connection (C. Parris, H. Zhang and D. Ferrari, ACM Multimedia Systems Journal, 1 (6) (1993) 267-283). We also presented several simulation experiments that proved the feasibility of the scheme and analyzed its performance. In this work we complete this proof of concept by implementing the DCM scheme and conducting several initial measurement experiments on this prototype. The implementation utilized the data delivery protocols of the Tenet Real-Time Protocol suite and the Simple Network Management Protocol version 1 (SNMPv1) as the control or management protocol. The measurement experiments indicated that, although the scheme is indeed useful, there are several limitations caused by the use of SNMPv1.