The network is a central resource for a terminal server. If the network does not perform properly or fails, many users will no longer be able to work.

Optimizing the Network Connection

The properties of the network adapters can be changed through Start\Control Panel\Network Connections and the properties of the appropriate LAN connection. The configuration of the physical adapter should not include an autodetect of the network speed or automatic negotiation of duplex options. These settings must be preset to avoid errors that can cause a significantly reduced network connection.

If network communication bottlenecks occur, it is recommended that the File and Printer Sharing for Microsoft Networks properties of the network connection be adjusted. Changing the Maximize data throughput for file sharing to Maximize data throughput for network applications often improves the terminal server’s performance.

Standard Troubleshooting Tools

In addition to the standard graphics tools, Windows Server 2003 includes a number of troubleshooting programs to handle network problems. The following overview lists the available tools, their purpose, and their areas of use.

  • Arp Displays the Address Resolution Protocol (ARP) table on the local computer. Arp -a shows the current IP cache resolution cache.

  • Hostname Indicates the current computer name.

  • Ipconfig Displays and updates the current TCP/IP configuration. Ipconfig/all shows all relevant network parameters.

  • Nbtstat Reviews the status of NBT connections (NetBIOS over TCP/IP). Nbtstat -c displays the local cache, including the IP addresses of the NetBIOS names.

  • Netstat Displays log statistics and the status of all current TCP/IP connections. Netstat -a shows active TCP/IP connections, Netstat -r indicates active routes.

  • Nslookup DNS server query to verify data records, aliases, and other services.

  • Ping Verifies the TCP/IP configuration and connection to other computers. Ping -a <Computername> translates the address into a name.

  • Route Output and modification of routing tables. Route print displays active routes.

  • Tracert Verifies the route to a remote computer.

Skillfully sequencing these commands and output of the results into a file can bring about amazingly powerful analysis tools.

Accelerating RDP and ICA

If remote users are able to type very quickly, screens on Terminal Services clients sometimes tend to hang. This is true for both the RDP and the ICA protocol. To improve terminal server response times, it is possible to change the time that the terminal server waits until it transmits buffered data packages. The shorter this time is, the smaller the data packages are. The time is set via the OutBufDelay registry value. This method increases the frequency with which the data packages are sent. However, this change also gives rise to a slightly increased network load.

The output buffer settings are always related to a protocol as it was created in the Terminal Services Configuration. For RDP, these two registry paths are relevant: HKLM\System\CurrentControlSet\Control\Terminal Server\Wds\Rdpwd\TDS\tcp\OutBufDelay and HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\rdp-tcp\OutBufDelay. The parameters specify the number of milliseconds that a terminal server buffers data before transmitting it to the client. The default value is 0x64; half of that value should improve overall system response.

The ICA protocol registry entries are saved under HKLM\System\CurrentControlSet\Control\Terminal Server\Wds\Icawd\TDS\tcp\OutBufDelay or HKLM\System\CurrentControlSet\Control\Terminal Server\WinStations\ICA-tcp\OutBufDelay.