Hi Brian. I don't recall the specifics of what prompted this question, but I have learned much about LTM/TCP in the intervening years. One thing that I have learned which is pertinent to questions about the Receive Window is to understand which direction data is flowing. If I read my description again closely, it sounds like the data is flowing from server to client. And if that's the case, then I should not have expected the LTM's Receive Window to increase, because it is not receiving data - it is SENDING. And so it's the *client's* Receive Window which should be increasing quickly, not the LTM's. If the data was flowing in the opposite direction, i.e. the client was POSTing data to the server, THEN I would expect the LTM's receive window to increase. And believe me - it does.
So in your case, is that the behavior you are asking about - the LTM's Receive Window does not open when sending data to the client? Or is the scenario a bit different? I am always interested in diagnosing TCP issues...