Tftp issue with new devices (9300 & 3850)

[ittechk4u1]

cant copy the config files from these swicthes...

error logs 

DC1XCIK1#copy startup-config tftp:
Address or name of remote host []? 192.168.19.8
Destination filename [DC1xcik1-confg]?
!.....
%Error writing tftp://192.168.19.8/DC1xcik1-confg (Timed out).....

I can ping tftp server and vice versa from laptop

ip tftp source interface is also configured...

what could be the reason..?

Thanks in advance

[ittechk4u1]

Leo,

But same TFTP server is working for all other devices (example: router, firewall...etc). Only not working for Switches!

layout:

Thanks again.

[Richard Burts]

Thanks for the debug output. It does confirm that the tftp request was sent to the server and that a response was received. This is good to know. I see in the debug output that the server responds with a block size of 8192 and the switch is sending 8192 length packets. Given the path that this data takes, and given the description in a previous response that part of the path may be over vpn, I wonder if the issue is about packet size and possible need to fragment. Is it possible to configure the server to specify a smaller block size?

HTH

Rick

[ittechk4u1 · Accepted solution]

Now issue have been resolved by using the command;

"ip tftp blocksize 512"

I dont undersatnd why cisco says that "By default, the Catalyst 3850 uses a TFTP block size value of 512"

Thank all of you.

[Richard Burts]

Thanks for the update letting us know that the problem is solved. I am glad that my suggestion pointed you to the solution.

I believe that the explanation to your follow up question is that while it is correct that 3850 will default to block size of 512 that the block size for any particular transfer is negotiated. And if the server negotiates 8192 then the 3850 will use that block size.

HTH

Rick

[ittechk4u1]

Thanks Burts.

Intereseting fact:

1. 3850 was having default Block size of 512 and it didn't work.
2. Then I changed block size to 8192 on 3850 and result was same as step1.
3. Finally I changed again to 512 on switch and it worked.

Thanks

[Donato Fabrzio]

Hello,

I had same issue.

i solved to configuring a block size of 4096

With block size 8192 don't work

With blcok size 4096 work fine.

> ip tftp blocksize 4096

Regards

[p.nordlien]

This helped me too. 

When I tried the command 'copy tftp: flash:' the first time, it started off well and stopped half way in the transfer. On the following tries it timed out over and over again. Applying the command 'ip tftp blocksize 512' allowed the transfer to complete.

Thanx everyone. 

[Richard Burts]

Thanks for sharing your experience with this. It may help some other participants in the community.

[NetworkTheWorld]

Confirmed to work on cisco 9300 as well,

I experienced the issue and was resolved by changing the block size.

[STEVE GLICK]

Thanks--your post isn't recent but it solved a frustrating problem I've had. 

[Richard Burts]

Thanks for sharing your experience. As I said in a previous post in this discussion "sharing your experience with this. It may help some other participants in the community." And you are one who has been helped in this discussion. 

[Leo Laohoo]

I have forgotten about this:  CSCvq01204 (C3K switches 16.6.6 TFTP timed out when blocksize is set to 8192)