TCP/IP unacknowledged data storage
<p>we have a windows 2003 server which is accessed from ~100 clients connected through a GB  network and ~400 clients connected outside through a T1 (1.5Mbis/s) line to the internal network. The clients ask the server for data with a size of 300 - 400kB. </p>

<p>The server shows a constant network load of ~1.6Mbis/s and all users have a poor response time. </p>

<p>My assumption is that on packet takes a long time on the T1 line until its acknowledge is received and the "buffer" of the unacknowledged data is full so the local users must wait for a free slot in the buffer. </p>

<p>Is this a possible reason for our problem? And where does this buffer reside (NIC / TCP-Stack / ...)?</p>