Ephemeral TCP Port Limits

This topic explains how to increase ephemeral TCP port limits for use with VMware Tanzu GemFire.

By default, Windows’ ephemeral ports are within the range 1024-4999, inclusive. You can increase the range.

If you repeatedly receive the following exception:

java.net.BindException: Address already in use: connect

And your system experiences a high degree of network activity, such as numerous short-lived client connections, this could be related to a limit on the number of ephemeral TCP ports. While this issue could occur with other operating systems, typically, it is seen only with Windows due to a low default limit.

Perform this procedure to increase the limit:

1. Open the Windows Registry Editor.

2. Navigate to the following key:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameter
   

3. From the Edit menu, click New, and then add the following registry entry:

   Value Name: MaxUserPort 
   Value Type: DWORD  
   Value data: 36863
   

4. Exit the Registry Editor, and then restart the computer.

This affects all versions of the Windows operating system.