UBR++: improving TCP performance over ATM-UBR using a new packet discard scheme

A new packet discard scheme called the forgiveness mechanism that can be plugged into the existing buffer management schemes of an ATM switch is developed. This new scheme remarkably enhances both the throughput and fairness of TCP running over an ATM-UBR service. Our scheme does not require per VC accounting but per VC-state where only one bit is needed The focus here is on demonstrating and analyzing the effect of the forgiveness mechanism when plugged into the early packet discard (EPD), selective discard (SD) and fair buffer allocation (FBA) buffer management schemes in low latency networks. This paper explains the concepts behind the new scheme and demonstrates ifs effect on TCP performance using the ATM/HFC network simulator version 4.1 released December 1998 by NIST.