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New Member

IOS upgrade TFTP timeout

I am trying to upgrade a 2851 router using TFTP but the connections keep timing out. It goes along fine for about 13MB of the file then timeouts a bunch of times and stops working. When I use FTP to do the upgrade I don't have any issues. Any suggestions on what could be wrong?

  • Network Management

Re: IOS upgrade TFTP timeout

Do you have exec-timeouts on your vty sessions ? If so either temporarily turn them off or extend them to like 60 minutes . I think ftp runs faster and is probably finishing before the vty session times out. For some reason it doesn't see the transfer as valid data and if you have it set to like 10 minutes it will terminate the session.


Re: IOS upgrade TFTP timeout

I had a similar case: TFTP was timing out, FTP was going very slow; turned out to be a duplexity mismatch.

Hall of Fame Super Silver

Re: IOS upgrade TFTP timeout

I think there is value in the suggestion to be careful about the inactivity timeout of your vty and certainly there is value in verifying that duplex settings match on interfaces that will carry this traffic.

I have two other suggestions.

- Some implementations of TFTP server have hard coded values for packet timeout and for number of retries that the server will attempt before aborting the transmission. Some implementations of TFTP server establish default values for these and allow you to change the values. If your current TFTP server has hard coded values perhaps you should switch to one that lets you change the values. (One example of these is the 3CDaemon from 3Com which I like). If your current TFTP server allows you to change the values perhaps you should increase both the timeout value and the number of retries.

- If you are transmitting over links that are slow and perhaps congested and where packet loss may be an issue I think that there are several advantages to using FTP to do image transfers. I have recently done some comparisons of transfering images with TFTP and with FTP. I have found that FTP is a much more efficient trasfer of large files. For smaller files like config files the difference is not significant. But for image files which can get pretty big the difference is significant. FTP is much faster (and will take fewer packets to do the transfer since TFTP forces small packets and FTP uses maximum size packets). So my second suggestion is to not worry about TFTP for these transfers and just use FTP.