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Feb 2nd, 2009
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I tried to download flash image from a 2811 integrated service router using TFTP server. After downloading for a while, it says unknown error. I doubt it as file size limitation for TFTP, but not sure. Would any body please have any ideas for this,


~~ subharoj

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Richard Burts Mon, 02/02/2009 - 12:24
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If it runs for a while and then has an error is it possible that it suffered a timeout - that there is enough packet loss to interfere with the TFTP transmission? While it was running were you getting mostly the symbol ! to indicate successful transmission or were you getting some symbol . to indicate missed packet?

Is it possible that you are copying into flash and that there is not really enough room in flash for the new image?

It might also be possible that there is an issue with the size of the image. Images are getting larger and depending on the feature set some of them are now very large. This does cause a problem for some implementations of TFTP server. The traditional implementation of TFTP did have a restriction on file size that could be transmitted. It might be worth while trying a different TFTP server (I see lots of positive comments about tftpd32 as a server which does not have limits on file size). Or I frequently suggest to people transferring large images to try FTP instead of TTP. The transfer with FTP is faster and more efficient than a transfer with TFTP.



Yudong Wu Mon, 02/02/2009 - 12:25
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Yes, there is a size limitation by using TFTP. I don't remember the exact number. It might be around 16M. You can try other way like ftp.

Leo Laohoo Mon, 02/02/2009 - 15:52
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What is the total size of the file you are trying to d/l? What is the TFTP client you are using?

If it's bigger than 16Mb, try using TFTP32 (

Does this help?


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