In this paper we investigate the network performance of TCP hosts and gateways employing New Reno TCP using a parallel simulator. The gateway adopts the random early detection (RED) scheme and proactive congestion control mechanism to enforce fair sharing among competing TCP connections. The test network is modeled using PARSEC. The simulation reveals that the RED gateway drops only a small number of packets, and utilization of the bottleneck link on the RED gateway is less than 75%. The number of retransmission timeouts recorded at the TCP senders is also small. Moreover, increasing the bandwidth of the gateway input links does not substantially improve the network performance, while increasing the number of input links is very effective. Key words: congestion control, New Reno TCP, parallel simulation, PARSEC, random early detection.