Detailed information for the notes.ini Keyword: 


Short Description: Enable / Disable the Nagle algorithm which is used by TCP connections.


The Nagle algorithm is named after it's author, John Nagle, of RFC896. The algorithm was designed in the 1980’s to address network congestion caused by a "small packet" problem. When TCP is used to transmit one byte of data, the overhead is a 40 byte header. Applications like Telnet send a lot of 1 byte keystrokes over TCP, which can cause a lot of small packets on the network. The small packet problem can cause congestion on a heavily used network.

The Nagle algorithm is designed to address this issue. Small amounts of data are buffered as long as the connection is still waiting for acknowledgement (ACK) from the remote host. Once the expected ACK arrives, buffered data will be sent out. The algorithm assumes that every packet will get an acknowledgement promptly.

The Nagle algorithm interacts badly with TCP delayed acknowledgment. The delayed acknowledgment, as the name suggested, does not acknowledge every packet received. It acknowledges after it receives a burst of packets together.

Disable the Nagle algorithm using the notes.ini parameter Debug_PD_Nagle_Off=1

Default value:

UI equivalent:

Applies to:

Entry created by:
Bastian W.