Wireshark · Ethereal-users: Re: [Ethereal-users] TCP ACK packets with data in them...

[Guy Harris <guy@xxxxxxxxxx>]

On Thu, Feb 27, 2003 at 05:34:31PM -0800, Bob Eby wrote:
> I've been using ethereal for a while now to diagnose network problems
> and test software.  Recently I've been working on a Java application
> that sends and receives TCP data using the java.nio package.  In a
> recent sniffer trace I see examples of TCP ACK packets that contain
> large amounts of data that resembles what I'm trying to send.  At the
> same time I *don't* see PUSH/ACK packets containing this same data.

So is the problem just that the PUSH bit isn't being set on some data
segments?

If so, that might just be a question of what the OS on which you're
running chooses to do in its TCP stack.

If it has no API to allow a sending application to force a push, it's
not a problem in java.nio, as there's nothing java.nio can do about it
(except *maybe* write in a fashion that triggers pushing, *if* the OS's
stack does a push if it infers from the writes being done that a push
should be done - I've no idea whether any OSes do that).

If it does have such an API, then it's a problem with java.nio only to
the extent that it doesn't offer, say, a "push" method - but perhaps
they didn't think exposing the notion of pushes was a good idea.