SYMPTOMS :
What's UP Active monitors change every times from UP to DOWN and DOWN to UP and What’s UP return error “Failed to connect to w.x.y.z User=[username] Error=The RPC server is unavailable” and error message “DCOM was unable to communicate with the computer w.x.y.z using any of the configured protocols” in windows event log.
Event Type: Error
Event Source: DCOM
Event Category: None
Event ID: 10009
Date: 19.05.2009
Time: 14:59:03
User: N/A
Computer: [COMPUTER]
Description:
DCOM was unable to communicate with the computer w.x.y.z using any of the configured protocols.
CAUSE :
- Many TCP Connections Are Established for COM+ Proxy/Stub
- COM+ Applications Consume All Available Client Ports Between 1024 and 5000 and Cause High CPU Utilization
RESOLUTION :
The default maximum number of ephemeral TCP ports is 5000 in the products that are included in the 'Applies to' section. A new parameter has been added in these products. To increase the maximum number of ephemeral ports, follow these steps:
- Start Registry Editor.
- Locate the following subkey in the registry, and then click Parameters:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
- On the Edit menu, click New, and then add the following registry entry:
- Value Name: MaxUserPort
- Value Type: DWORD
- Value data: 65534
- Exit Registry Editor
- Restart the computer.
Description:
This parameter controls the maximum port number that is used when a program requests any available user port from the system. Typically , ephemeral (short-lived) ports are allocated between the values of 1024 and 5000 inclusive.
Note :
An additional TCPTimedWaitDelay registry parameter determines how long a closed port waits until the closed port can be reused.
MORE INFORMATIONS :
http://support.microsoft.com/kb/196271/EN-US/
http://support.microsoft.com/kb/290512/EN-US/
http://support.microsoft.com/kb/301512/en-us
http://support.microsoft.com/kb/910695/en-us
http://support.ipswitch.com/kb/WG-20020424-DM01.htm