What is the Nagle algorithm?
The Nagle algorithm is an optimization to TCP that makes the stack wait until all data is acknowledged on the connection before it sends more data. The exception is that Nagle will not cause the stack to wait for an ACK if it has enough enqueued data that it can fill a network frame. (Without this exception, the Nagle algorithm would effectively disable TCP’s sliding window algorithm.) For a full description of the Nagle algorithm, see RFC 896. So, you ask, what’s the purpose of the Nagle algorithm? The ideal case in networking is that each program always sends a full frame of data with each call to send(). That maximizes the percentage of useful program data in a packet. The basic TCP and IPv4 headers are 20 bytes each. The worst case protocol overhead percentage, therefore, is 40/41, or 98%. Since the maximum amount of data in an Ethernet frame is 1500 bytes, the best case protocol overhead percentage is 40/1500, less than 3%. While the Nagle algorithm is causing the stack to wait fo
