Strange double ACK in TCP/IP

Hi --

I have been tracking a TCP/IP stream that's going between a TINI 
(192.168.1.250) and a Win2K machine (192.168.1.100).

Strangely, it appears that when the TINI ACKs a packet from the PC, it ACKs 
twice ... once immediately after receiving the PC's packet, and another a 
short while later.

The main difference between the ACKs appears to be in the window frame 
size. The second one always appears to be a window frame size of 4096, and 
the first one appears to be the 4096 less the size of the packet actually 
sent (roughly).

Based on this, I would speculate that TINI does an ACK immediately when it 
receives the packet, telling the sender how much buffer the TINI has left. 
And then, when my application reads the buffer, TINI sends another ACK to 
say that it has more buffer space available.

Is this what's going on?? Why is the second ACK necessary or desirable???

The latest version of Ethereal (v10) seems to complain about this behavior.

What's the scoop?

Thanks.





vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
: Barry Demchak               :
: Torrey Pines Software, Inc. :
: http://www.tpsoft.com/      :
: (858) 452-8700              :
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 

_______________________________________________
TINI mailing list
TINI-6tN4nzCoH/[email protected]
To UNSUBSCRIBE, edit your profile, or see list archives:
http://lists.dalsemi.com/mailman/listinfo/tini