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Re: Is nagle disabled?

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Hi there


On 10/09/16 13:37, Nicolas George wrote:

> Le quintidi 25 fructidor, an CCXXIV, Rob van der Putten a écrit :
>> So the question should have been 'Is delayed ack disabled'.
>> I have a hard finding decent information on the subject, so I did a bit of
>> experimentation;
>> I send tiny bits of data (two bytes at a time) to a little echo  server. As
>> it turns out, the use of delayed acks and therefore nagle, depends on the
>> time between sending the bits of data and the RTT.
>
> I do not think you can really test delayed ACK with an echo server: the
> principle of delayed ACK is to leave a little time to the application to
> send a reply, because then the ACK can be bundled with the reply, saving a
> packet.
>
> With an echo server, the reply comes immediately, never letting the delay
> for the ACK expire.

I use netcat6. From man nc;
nc6 --continuous --exec cat -l -p <port>
So the data goes from nc to cat and then back to nc.

Timestamps (epoch.microseconds) are dumped to a file on transmission and 
to an other file on reception of the 'echo'. Further check with tcpdump. 
Experiment on LAN and experiment over DSL;
When the time between the bits of data is larger then the RTT, data is 
send at two bytes per TCP packet.


Regards,
Rob

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Thread

Is nagle disabled? Rob van der Putten <rob@sput.nl> - 2016-09-09 16:00 +0200
  Re: Is nagle disabled? Stefan Monnier <monnier@iro.umontreal.ca> - 2016-09-09 18:30 +0200
    Re: Is nagle disabled? Rob van der Putten <rob@sput.nl> - 2016-09-09 20:00 +0200
      Re: Is nagle disabled? Rob van der Putten <rob@sput.nl> - 2016-09-10 13:30 +0200
        Re: Is nagle disabled? Nicolas George <george@nsup.org> - 2016-09-10 13:40 +0200
          Re: Is nagle disabled? Rob van der Putten <rob@sput.nl> - 2016-09-10 14:00 +0200
            Re: Is nagle disabled? Nicolas George <george@nsup.org> - 2016-09-10 14:10 +0200

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