Exposed buffering and sub-datagram flow control for ATM LANs

We implemented an ATM network interface featuring two novel techniques: exposed buffering and subdatagram flow control. Exposed buffering allows applications to send or receive data from buffers shared with the network interface, thereby avoiding the latency of data copying or VM manipulations. Separate buffer areas maintain user privacy. Sub-datagram flow control uses feedback from the receiver to pace datagram transmission in small bursts according to the buffering available and eventual loss detected. This enables higher-level protocols or applications to use large transmission units and better amortize per-packet protocol overheads even if the network has limited buffering and no flow control. Our experiments show that these techniques can considerably improve latency, throughput, and congestion handling in ATM LANs