Design issues for providing minimum rate guarantees to the ATM unspecified bit rate service

We describe proposed enhancements to the ATM unspecified bit rate (UBR) service that guarantee a minimum rate at the frame level to the UBR VCs. These enhancements have been called guaranteed frame rate (GFR). In this paper, we discuss the motivation, design and implementation issues for GFR. We present the design of buffer management and tagging mechanisms to implement GFR. We study the effects of policing, per-VC buffer allocation, and per-VC queueing on providing GFR to TCP/IP traffic. We conclude that when the entire link capacity is allocate to GFR traffic, per-VC scheduling is necessary to provide minimum throughput guarantees to TCP traffic. We examine the role of frame tagging in the presence of scheduling and buffer management for providing minimum rate guarantees.