cURL / Mailing Lists / curl-library / Single Mail


Disabling Nagle Algorithm

From: John Coffey <>
Date: Tue, 25 Nov 2014 22:07:06 -0500

Hello again,

I am trying to connect a PowerPC based embedded FTP client using curl
7.39.0 to another embedded FTP server running a proprietary embedded FTP
server. If I replace the PowerPC client with the same ftp client
application hosted on a PC everything works fine. The problem exhibits
itself on the embedded target in the form of increased ACK delays - the
second screen shot looks like it is exhibiting the Nagle timings as it
encounters TCP Window Full and consequent Re-transmissions. I tried
setting the TCP_NODELAY as it is one of the hints towards disabling the
Nagle algorithm - however this did not seem to make any difference. The
first screenshot below shows the negotiated options between the client
dlmu-w and the server proc1 while the second screenshot shows when things
go wrong.

Ideally in order to get this to work correctly we would like to almost have
the data packets immediately ack's in a sort of lock step approach - a
little similar to the way TFTP works.

Any help in resolving this would be much appreciated

John Coffey

[image: Inline image 1]

[image: Inline image 2]

List admin:

image.png image.png
Received on 2014-11-26