Topic: XTS database downloads crashing at end of file transfer

[EV607797]

I'm having a consistent issue when obtaining database backups from XTS systems via modem. I'm using E-Com and it seems to perform just fine until it reaches the end of the file transfer. Instead of closing like normal and saving the file, it sits there and hangs, accumulating block errors or protocol errors until I give up and cancel it. Of course, the two hours spent waiting on the download is completely lost. I do have better luck using XTS-ADMIN and doing multiple partial downloads. This seems to be happening more and more, in fact it's on every one I try now. I am using a fresh installation of E-Com and a new USR modem, and aside from downloads, everything works perfectly. Any ideas?

[NFCphoneman]

Do you think it has anything to do with VoIP. Not that you're using VoIP directly, but who knows how call traffic is now routed between your modem and the XTS modem. Does it happen at slower speeds?

[EV607797]

Larry, I thought about that, but I'm not using IP here (who knows what's happening in between?), and it is a 5ESS copper line at most of the sites I'm working with.  We insist that the customer have a real copper line for 911 purposes and failover operation.  If it was an IP issue, I would think that the failures would occur throughout the process, not exactly at the end of the file transfer each time.  It can be a large file or small; when it gets to the end, the same thing happens every time.

[MacGyver]

Ed, as I've mentioned before, since you and Larry are the Vodavi Gods, I'm not going to begin to hang with you guys at the system level, but I have some thoughts from a TCP/IP point of view.

I was thinking about the TCP/IP Checksum.  There could be corruptions happening all along the way, but when the Checksum attempts to calculate, could that be where the failure is causing the issue?  I mean we would expect it to fail, but without sniffing packets it's hard to know for sure.  BTW, sniffing packets would be a good place to look, but in the absence of that, have you tried going back to basics and dropping the baud rate and trying to move a very small file?

Larry, wasn't there something in the old dial ups about error correction and was that related to the Xon/Xoff?  It's been too many years.

It would almost be nice to try some sort of UDP transfer and see if it flies. 

[EV607797]

Trace, that's what's so frustrating:  I can use a utility that allows partial database downloads and even at maximum speed (19.2KBps), those portions come through just fine.  I've tried using different protocols, such as the standard (XModem) and also XModem-CRC, and others.  I know that we've never had to make any changes to these settings for downloads and that plain old XModem worked fine.  I have compared identical database backups that were gathered in the past and determined that it is precisely when the last byte has been transferred that the process just stops.  After numerous timeouts, I end up just canceling the process.  It's as if the final tidbit of the handshaking process never comes through.  I'm fairly confident that the KSU sends the final byte to end the transfer, but my modem or software isn't seeing it.  I know this because after I cancel the transfer at the "end", the KSU is still sitting there and responsive.  It even lets me start the transfer process again if I want to.  I'm pretty sure it's on my end somehow, since several identical systems are behaving the exact same way.  I just don't know where that last byte is going to signal my software to save the file and end the transfer.

This is Vodavi's proprietary ECOM terminal emulation software that has always been very reliable.  Maybe I'll try with another computer and modem using Procomm to see if there's any difference.  Thanks for the insight so far.

[EV607797]

Now that I think about it, the problem I'm having is with a new PC using Windows 10 and a new USR USB modem.  I had to run the ECOM software in compatibility mode for Windows 7 in order to get the software to install.  I wonder if this might be my issue?  My desktop PC that never fails me is running XP with a real PCI type internal modem.

Is there an inexpensive or free terminal emulation program out there that I might try instead of ECOM?  I tried PUTTY, but I didn't see the file transfer capabilities that I need so I didn't mess with it further.  I saw that even Procomm has a new version 4 available, but when I tried to download it, nothing seemed to happen.  I sure don't want to go buying it until I know it works for my situation.

[telemarv]

Ed, you're probably on the the right track and you have win 10 compatibility.

I suggest you down load a free virtual machine such as VirtualBox https://www.virtualbox.org/wiki/Downloads and install win 7 or xp in the box. Then you can install your proprietary software in the virtual 7 (or xp).

Win 7 came with a virtual XP but with Win 10 Microsoft stopped doing that.

[MacGyver]

Ed, you're on the right track.  I would bet on it.

I'm not familiar with the program Marv suggested, but I have used DosBox on Win7 machines with great success to run an old Inter-tel terminal program.  Procomm is where I was going next, but you beat me to it.  If I still have my copy of PC it's on 5.25" disks.