A versatile RED-based buffer management mechanism for the efficient support of Internet traffic

This paper presents an evaluation of various GFR (Guaranteed Frame Rate) implementation proposals. By means of extensive simulations performed in different network environments we compare two ATM Forum example implementations, namely the "simple FIFO-based GFR.2 implementation" and the "per-VC threshold and scheduling implementation". The lessons learned from this study are as well applicable to non-ATM network technologies. Modifications to the "per-VC threshold and scheduling mechanism" like a different CLP interpretation and a RED (Random Early Detect) based buffer management mechanism are proposed and evaluated. The basic "per-VC threshold and scheduling mechanism" and its RED enhanced version are evaluated both in packet discarding and packet marking mode. In its packet discarding mode, the mechanisms act as buffer acceptance mechanisms, prohibiting packets to access the switch buffer in case of congestion. In its marking mode, it can be used to signal impending congestion by means of ECN (Explicit Congestion Notification) marking. Finally the performance of these mechanisms is evaluated both for TCP-Reno and TCP-Sack and recommendations are made with respect to the use of RED, ECN and TCP-Sack.