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Article #25533: Configuring TCP parameters on Windows NT

Problem:
The timeout value for a lost connection is too long.
Can I configure it?

Solution:
On Windows NT there are three TCP configuration parameters 
that are of interest to managing an active connection in Interbase:

  KeepAliveTime - The parameter controls how often TCP attempts 
  to verify that an idle connection is still intact by sending a keep 
  alive packet. If the remote system is still reachable and functioning, 
  it will acknowledge the keep alive transmission.  Keep alive packets 
  are not sent by default. This feature may be enabled on a connection 
  by an application.

    Value Type:   REG_DWORD - Time in milliseconds
    Valid Range: 1 - 0xFFFFFFFF
    Default: 7,200,000 (two hours)

  KeepAliveInterval - This parameter determines the interval separating 
  keep alive retransmissions until a response is received  Once a 
  response is receive, the delay until the next keep alive transmission is 
  again controlled by the value of KeepAliveTime. The connection will be 
  aborted after the number of retransmissions specified by 
  TcpMaxDataRetransmissions have gone unanswered.

    Value Type: REG_DWORD - Time in milliseconds
    Valid Range: 1 - 0xFFFFFFFF
    Default: 1000 (one second)

  TcpMaxDataRetransmissions - This parameter controls the 
  number of times TCP will retransmit an individual data segment 
  (non connect segment) before aborting the connection. The 
  retransmission timeout is doubled with each successive 
  retransmission on a connection. It is reset when responses 
  resume. The base timeout value is dynamically determined by 
  the measured round-trip time on the connection.

    Value Type: REG_DWORD - Number
    Valid Range: 0 - 0xFFFFFFFF
    Default: 5

These parameters are found in the Registry in the following location:

  HKEY_LOCAL_MACHINE
   SYSTEM
    CurrentControlSet
     Services 
      Tcpip
       Parameters

To configure these and other available TCP parameters see 
the document titled Q120642 on the searchable knowledgebase 
at www.microsoft.com, or navigate to the following location 
using a browser:

  http://support.microsoft.com/support/kb/articles/q120/6/42.asp

Last Modified: 26-OCT-00