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anonymous View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote anonymous Quote  Post ReplyReply Direct Link To This Post Topic: Telnet disconnects
    Posted: August 26 2004 at 5:57am
Hi -

We have a customer that is using telnet via Accuterm to an IBM AIX Unix server. Every once in a while, their frame relay connection loses it for a few seconds. Is there a timeout delay in Accuterm that will allow them not to loose connectivity during the connection loss.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PSchellenbach Quote  Post ReplyReply Direct Link To This Post Posted: August 26 2004 at 6:49am
While there is no setting in AccuTerm that will maintain a connection during a transient network outage, there may be some settings you can tweak in Windows TCP/IP.

I ran some tests with AccuTerm 2K2 (5.2a) on a Windows 2000 PC connected over a 10/100 lan to a Linux server. I simulated a network failure by disconnecting the cable between two ethernet switches - disconnecting the cable from the PC is not the same - Windows detects this and closes all connections in 8 to 10 seconds.

With a session open to the Linux machine, I entered a command at the command line and just before I pressed the ENTER key, I unplugged the cable. With the default Windows TCP/IP settings, the failure was reported in 20 seconds. If I reconnected the cable within 20 seconds, AccuTerm never noticed the interruption.

Next, I changed the Windows TCP/IP setting for the number of retransmissions from the default of 5 to 6. This increased the time before the failure was reported to 40 seconds. Changing the value to 10 increased it to 11 minutes! Windows TCP/IP doubles the timeout for each retransmission, to a maximum of 240 seconds (4 minutes), so the time before the connection is aborted increases exponentially as the number of retransmissions increases.

The actual base retransmission timeout is computed dynamically, but it looks like it probably starts at 0.3 seconds.

To change the number of retransmissions for Windows TCP/IP, you need to change or add a value to the Registry. Use Start->Run and type REGEDIT in the Open box and click OK. When the Registry Editor opens, expand the keys until you get to:

My Computer -> HKEY_LOCAL_MACHINE -> SYSTEM -> CurrentControlSet -> Services -> Tcpip -> Parameters. With the Parameters key selected in the left pane, double-click the TcpMaxDataRetransmissions value in the right pane. Enter a new value (hex or decimal - just check the right option) and click OK. If there is no TcpMaxDataRetransmissions value shown, the default of 5 is used. You can change from the default by adding this value: right-click in the right pane and select New->DWORD Value. Change the name to "TcpMaxDataRetransmissions" and double-click to change the value. Enter a number between 5 and ?? - in hex or decimal, and click OK. I believe a reboot is required for the change to become effective.

This may help make AccuTerm connections less sensitive to transient network failures.

Thanks,

Pete
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tcasora Quote  Post ReplyReply Direct Link To This Post Posted: November 05 2004 at 3:43am
Hi Pete,

Is there a TCP/IP folder in Windows 98? Couldn't find one for some reason.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PSchellenbach Quote  Post ReplyReply Direct Link To This Post Posted: November 11 2004 at 3:38am
Hi -

The setting for Windows 95/98/ME is in a different location: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\
MSTCP. The value name is MaxDataRetries. For Windows 95, this must be a DWORD value, and for Windows 98/ME is must be a STRING value.

Thanks,

Pete
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PSchellenbach Quote  Post ReplyReply Direct Link To This Post Posted: October 15 2014 at 7:24am
Here's a link to a Microsoft knowledge base article about adjusting TcpMaxDataRetransmissions:
http://support.microsoft.com/kb/170359
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