Huge thanks to our Platinum Members Endace and LiveAction,
and our Silver Member Veeam, for supporting the Wireshark Foundation and project.

Wireshark-users: Re: [Wireshark-users] is it Nagle?

From: "Bill Meier" <wmeier@xxxxxxxxxxx>
Date: Fri, 20 Jul 2007 11:40:30 -0400
Omar Balbuena wrote:

> After some research, I've 
> discovered it seems to be the Nagle Algorithm that's slowing me down, 
> and I've added the proper lines of code and it seems to have no effect. 
> But this looks like absolutely anything but Delayed Ack.
> 
> My question is:
> Is it really Nagle?

My answer would be no;

I seem to remember that the Nagle delay happens only when there is 
outstanding unacknowledged previously sent data when new data is provided by 
the program to the TCP stack.

After frame 4 there is no outstanding unacknowledged data so I doubt that the 
delay before 4 and 5 is due to Nagle.

That being said, I've no knowledge or experience of how Winsock works so the 
above may or may not apply.  

I do note one somewhat interesting thing.

The window size specified by ...129  is decreasing as it receives and acks 
data (65040, 65031, ...).
Altho perfectly OK, this is an indication on some (many ?) TCP stacks that 
the data is buffering up in the stack and not being processed by the 
receiving program.

To be perfectly honest: I would revisit:

> I am absolutely sure this has nothing to do with software processing,
> because such thing never happened with serial ports and modem
> communication using the exact same layers.


Bill Meier