SMS: "Unable To Locate <machine name>" w/Remote Control in WAN

• Microsoft Systems Management Server, version 1.2

SYMPTOMS

When trying to remote control a Systems Management Server client in a wide area network (WAN) environment, the following error messages may occur in sequence:

• Attempting To Locate <machine name>
• Trying Additional Protocols
• Unable To Locate <machine name>

CAUSE

On a TCP/IP WAN, communication over some routes may fail if intermediate network segments have packet sizes smaller than the communicating hosts, and routers do not send appropriate ICMP responses to this condition. A router that causes this condition is sometimes known as a "black hole" router.

The Windows NT Server PING utility is a great diagnostics tool that can help you find those "black hole" routers. Use the following PING command:

   PING -t -l 64000 <machine name>.

To resolve this problem, correct the configuration of the appropriate router.

WORKAROUND

To work around this problem, modify the following registry key.

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

1. Run Registry Editor (Regedt32.exe).

2. From the HKEY_LOCAL_MACHINE subtree, go to the following key:

         SYSTEM\CurrentControlSet\Services\<adapter name and number>
         \Parameters\Tcpip
   

3. On the Edit menu, click Add Value.

4. Add the following values:

         Value Name: MTU
         Data Type:  REG_DWORD
         Data: <1500 or Ethernet segment's MTU size>
   

5. Click OK.

6. Quit Registry Editor.

7. Shut down and restart Windows NT.