Avoid Incomplete Paste Operations with Echo Flow Control

Have you ever pasted to a remote machine only to realize later that some portion of the text from the clipboard didn’t arrive?  If so, you’re not alone.  Many network devices don't implement robust flow control – they can’t process data as fast as it is sent by SecureCRT®.

Is there some way to slow down the data transfer rate of SecureCRT so the remote device doesn’t get overloaded?

SecureCRT’s Line Send Delay session option can be used to slow down SecureCRT’s transfer rate.  However, choosing a line send delay value that is too high can result in poor paste performance.  A value that is too low can result in sporadic data losses if the remote device is otherwise overloaded.

Is there a better solution than using the Line Send Delay option?  Yes.  The concept is known as “echo flow control”, and here’s how it works:

1. SecureCRT sends the first line of text in the clipboard.
2. SecureCRT waits for the remote machine to echo the line. The wait is only as long as it takes the remote device to echo the line, so the process is automatically tuned to the remote device’s best performance at any given time.
3. SecureCRT then sends the next line of text from the clipboard.

Steps 2 and 3 are repeated until all lines from the clipboard have been sent. This method prevents overwhelming a remote host that does not implement flow control.

A “Paste with Echo Flow Control” script is available for download at the following location on the VanDyke Software forums:

http://forums.vandyke.com/showthread.php?t=10365

Here’s how to use the “Paste with Echo Flow Control” script:

1. Download the “Paste with Echo Flow Control” script from the page linked to by the aforementioned URL:

http://forums.vandyke.com/showthread.php?t=10365

Note: If you’re running SecureCRT on Windows, you can use either the .py (Python) or .vbs (VBScript) version of the script.  If you’re using SecureCRT on Mac OS or Linux platforms, use the Python version of the script since VBScript isn’t available on those platforms.

2. Use SecureCRT's button bar functionality to create a button to run the echo flow control script.  For more information about mapping a button to run a script, consult the SecureCRT button bar tip:  http://www.vandyke.com/support/tips/buttonbar.html  (see the section titled, “Create a button command to run a script”)
3. When connected to a remote device that drops data if it’s sent too fast, use the button you created in step 2 to send the data from the clipboard to the remote device.