When you're running a TN3270 application through the TN3270 service in Microsoft Host Integration Server 2010, the TN3270 session may stop running. When you try to re-establish the session, it starts to work again. When this issue occurs, you may see an instance of event 306 that resembles the following in the Application log:
Input from the client ::1 (port port_number) using LU LU_Name was ignored.
This issue occurs because of the overly brief time frame in which the TN3270 service receives data from the TN3270 client while it has not yet received a TCP acknowledgement for data that was previously sent.
Cumulative update information
The fix that resolves this problem is included in Cumulative Update 10 for Host Integration Server 2010.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.