2 a Simulation Study of Tcp Withthe Gfr Service

Recently, the Guaranteed Frame Rate (GFR) service category has been proposed to provide bandwidth guarantees with a simpler implementation than ABR in ATM networks. In this paper, we study the performance of TCP in LAN and WAN ATM networks supporting the GFR service category. We present simulations where each TCP connection is carried by one GFR VC with a minimum guaranteed bandwidth. We consider the proposed FIFO-based and WFQ-based switch implementations and evaluate their ability to eeciently support TCP traac. Our simulations show that with the proposed FIFO-based implementation for the GFR service category, TCP is unable to beneet from the minimum guaranteed bandwidth of the underlying ATM VC. With the proposed WFQ-based implementation, the performance of TCP is good in a LAN environment when no losses occur, but it becomes degraded in a WAN environment.