Microsoft's definition of this parameter is:

This parameter controls how often TCP attempts to verify that an idle connection is still intact by sending a keep-alive packet. If the remote system is still reachable and functioning, it will acknowledge the keep-alive transmission. Keep alive packets are not sent by default. This feature may be enabled on a connection by an application.

By default, this parameter is set to 7,200,000 milliseconds, or two hours. As you can see, any attempt to utilise this default setting in our scenario would prove useless as it's way outside our firewall session parameters. Simply reducing the value to less than thirty minutes (or what ever the firewall is configured to) results in more frequent TCP keep-alive packets being generated by the associated idle client and server sessions.

This ensures any session-based processes that separate the client and sever are kept refreshed and open.

Consequently, I have applied the following registry patches which inserts the following value:

This equates to twenty minutes, which is well within the firewall session limitation. Further tuning can be achieved by manipulating values that change the timing and interval of the keep-alive process. Configuring both the clients and the servers ensures bi-directional refreshing of all sessions.

The theory into practice.
I have applied this patch to many users who have been particularly prone to experiencing the "Requesting data" messages, and it has totally eradicated the problem. As stated at the beginning of this article, this message can appear because of numerous reasons and even with this fix, it may still be generated by further problems. It is at least an alternative option in potentially reducing its frequency. I would be delighted to here from anyone who finds this a successful resolution to their problem

Finally, the most ironic part of this is that the users who complain they suffer with this the most are the people who use Outlook the least.

Mark Craddock is an independent IT consultant based in the UK and can be contacted at mark.craddock@blueyonder.co.uk.