Putting the Crunch on Flaky Terminal Connections
Many organizations operate in a manner where all of its users rely on a connection to a Windows Terminal Server in order to run daily applications. One of the most frustrating things when dealing with this type of network is troubleshooting flaky connections to the Terminal Server. That is, connections that aren’t very reliable or very fast. You can usually recognize Terminal Server networks with flaky connections by sticking your head in an office and hearing a bunch of inappropriate yelling followed by “session locked up.”
One of the best ways to put the crunch on a flaky connection is by increasing the MaxRetransmissions settings. When a terminal server sends a packet to a client that is not returned it retries sending the packet a specified number of times before the session is terminated.
This setting can be modified by opening the registry editor and browsing to HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameter, and creating or editing the DWORD value TcpMaxDataRetransmissions. This is set to five by default, buy most people will at least double that. You will want to play around with this setting a bit on known flaky connections and see what is a best fit for you. Once set properly, you should hear quite a few less complaints regarding people being kicked out of their terminal sessions.
Chris Sanders is a consultant for KeeFORCE, one of the most popular network consulting firms in western Kentucky. Chris is the author of the book Practical Packet Analysis as well as several technical articles. His personal website at http://www.chrissanders.org contains a great deal of information, articles, and guides related to network administration, network security, packet analysis, and general information technology.