Method of implementing GFR service in large-scale networks using ABR control mechanism and its performance analysis

This paper proposes implementing guaranteed frame rate (GFR) service using the available bit rate (ABR) control mechanism in large-scale networks. GFR is being standardized as a new ATM service category to provide a minimum cell rate (MCR) guarantee to each virtual channel (VC) at the frame level. Although ABR also can support MCR, a source must adjust its cell emission rate according to the network congestion indication. In contrast, GFR service is intended for users who are not equipped to comply with the source behavior rules required by ABR. It is expected that many existing users will fall into this category. As one implementation of GFR, weighted round robin (WRR) with per-VC queueing at each switch is well known. However, WRR is hard to implement in a switch supporting a large number of VCs because it needs to determine in one cell time which VC queue should be served. In addition, it may result in ineffective bandwidth utilization at the network level because its control mechanism is closed at the node level. On the other hand, progress in ABR service standardization has led to the development of some ABR control algorithms that can handle a large number of connections. Thus, Ne propose implementing GFR using an already developed ABR control mechanism that can cope with many connections. It consists of an explicit rate (ER) control mechanism and a virtual source/virtual destination (VS/VD) mechanism. Allocating VSs/VDs to edge switches and ER control to backbone switches enables us to apply ABR control up to the entrance of a network, which results in effective bandwidth utilization at the network level. Our method also makes it possible to share resources between GFR and ABR connections, which decreases the link cost. Through simulation analysis, we show that our method can work better than WRR under various traffic conditions.