Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

TFTP Large Images

I am attempting to TFTP a Large Image to a a 6503 sup engin 7200. The TFTP starts and continues and never fails but Packet ACK reset to 0 on the tftp server and the file is resent, at no time does the TFTP or server stop. I have tried a number of TFTP servers and even used the TFTP server to transfare the Image from PC to PC to prove concept and file integrity. I have attempted to copy the required file to bootflash and compact flash. I have attempted to copy file to flash on 1841 router and same sesult. The process starts and never stops with file never arriving at destination.

The Image is approx 45mb and resets at approx 34mb.

Is this a known problem and is there a work around.

Many Thansk



Re: TFTP Large Images


Honestly telling i have never really tried doing a tftp transfer in cisco gear, with file size more than 32 mb.

But it looks like a known issue with the tftp protocol itself.

The original protocol has a file size limit of 32 MB, although this was extended when RFC 2347 introduced block-size negotiation.

It could be possible that your software has that limitation.

BTW, when you have tested transfer between two hosts, did you faced the same problem with file size.?

You can try with this tftp server, referred in cisco site.

Hope this helps.


Hall of Fame Super Silver

Re: TFTP Large Images

I agree with VJ that tftpd32 is a good choice for moving images that are very large. I have a slightly different suggestion: instead of TFTP try using FTP to move the file. FTP does not have the limitation on file size that TFTP does. And also FTP is a much more efficient protocol than TFTP for moving large files. You will find the time required to load the file will be considerably less with FTP as compared to TFTP (and the performance difference is more obvious the larger the file).



New Member

Re: TFTP Large Images

Many Thansk

The TFTP server i am using supports filesw larger than 32mb ans i can tftp between PC,s

I will check the tftp server you mentioned. in the mean time i set up a ftp server and copied the wimage without any issues however this is a non perfered method.


Re: TFTP Large Images


The original TFTP protocol has a file size limit of 32 MB, although this was extended when RFC 2347 introduced block-size negotiation in 1998

Additionally in the past I've found problems even with images larger than 16MB

What I don't know is if actually IOS support the RFC extension for being able to transfer images grater than 32 MB.

If not you can use ftp or RCP I allways prefer this.


New Member

Re: TFTP Large Images

tftp limited use ftp

New Member

Re: TFTP Large Images


My understanding of this issue is that it is a limitation of TFTP. The RFC TFTP is designed around is not designed to handle images larger than ~ 32MB. So TFTP is not a protocol to use to transfer images larger than 32MB, you need to try another protocol like FTP, RCP or SCP. These can handle the larger files.