Concurrent TCP connection RRS feed

  • Question

  • Hello,


       Were running a home grown app on a Windows 2008 R2 Enterprise server.  The developemnt team would like to know how many concurrent TCP connections can be made and what is the max allowed open ports? Also is there a way to see this in the registry?



    Thank you for your help!


    Friday, November 18, 2011 5:39 PM


All replies

  • In previous versions of Windows server operating systems there was parameter
    Data type          Range                  Default value
    REG_DWORD   0x0–0xFFFFFE   0 

    Friday, November 18, 2011 9:03 PM
  • Thank you for your reply,

    I don't see that registry setting in Windows 2008.  Could it be in a different place?
    Friday, November 18, 2011 9:47 PM
  • It seems it depends on the edition. Since you are using the Enterprise edition, there shouldn't be any limit on the number of active connections.




    Friday, November 18, 2011 11:26 PM
  • I have not found specific data for W2K8 R2. On the other hand take into account the following:

    1. Even if the specified registry parameter is not used in default registry, it is posssible for  some of them to include these in registry and they play the required role. 

    2. The theoretical limit is one side of problem and the real values are the second. Whenever there is queue for connection resources longer that one, you know that you have a problem.

    3. I suggest to got to solution from other side. You expect that you will need a specified number of connections a that is the way to result(s), because you can come to the conclusion, that the only solution is grouping multiple cards and load balancind, teaming,etc are needed. (Performance monitor is your friedn in this game.)



    Saturday, November 19, 2011 10:35 AM
  • Hello, 

    Refer following...

    Max tcp/ip connections on Windows Server 2008


    Configure the max limit for concurrent TCP connections




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    • Marked as answer by Rick Tan Monday, November 28, 2011 2:51 AM
    Saturday, November 19, 2011 11:01 AM
  • Hi,

    Thank you for your post.

    I agree with Configure the max limit for concurrent TCP connections article.

    I don't see that registry setting in Windows 2008.  Could it be in a different place?
    TcpNumConnections and MaxUserPort are not added in Windows 2008 by default, you could add it manually.

    Rick Tan

    Tuesday, November 22, 2011 6:31 AM
  • Thank you all for your replies.  Are the below statements accurate if you take server specs and application limits out of the equation.


    max_user_ports = 3977

    numTcpConnections =  16,777,214

    timeouts = 72 seconds


    Thank you,

    Tuesday, November 22, 2011 3:57 PM
  • Hi,

    on OS before Vista: 3977 (rang 1024-5000)
    on OS Vista and later Version: 16384 (rang 49152-65535)

    TcpnumConnections =  16,777,214
    KeepAliveTime = 7200,000 milliseconds =2 hours

    Rick Tan

    • Marked as answer by Rick Tan Monday, November 28, 2011 2:51 AM
    Wednesday, November 23, 2011 8:32 AM
  • Thank you all for the help!!!
    Monday, December 5, 2011 10:52 PM