Copy TFTP fails from 4431 routers

[kkinkaidcc]

Hi, I have setup a pair of 4431s (IOS XE 16.12.06) on a network but can't get any

 copy tftp 

commands e.g.

copy run tftp

to work on either 4431. I have tested the tftp server using another cisco router on the same subnet and I don't have any issue.  I can ping from the 4431s to the tftp server without issue.  I also ran tcpdump on the tftp server while trying to do a

 tftp copy

but I didn't see any connection attempts. Is there anything special to enable TFTP from a 4431 or anything else I can do to troubleshoot?  Thanks!

Here's a command that I can run to get a failed transfer:

mp-gw3-ncss#copy run tftp://[ip address]/[filename].cfg
Address or name of remote host [ip address]?
Destination filename [filename.cfg]?

.....
%Error opening tftp://[ip address]/[filename].cfg (Timed out)
mp-gw3-ncss#sho tech | redir
mp-gw3-ncss#sho tech | redirect tftp://[ip address]/[filename].txt
.....
%Error opening tftp://[ip address]/[filename].txt (Timed out)
mp-gw3-ncss#

[Georg Pauwen]

Hello,

what syntax do you use, and what is the error that is being displayed ?

[kkinkaidcc]

Hi,  I updated the posts with those details.

[Richard Burts]

Yes you updated. But so much of the detail is redacted that it is difficult to know what parts might be significant. If this is tftp within your network then the addresses are probably Private addresses. So what is the reason to redact them. 

After you attempt the tftp are there any entries in syslog that relate to this activity?

If you can ping from the router to the server that demonstrates basic IP connectivity. Which is good. Is it possible that on this router (or somewhere along the path to the server) is a security policy that is preventing tftp?

[Leo Laohoo · Accepted solution]

ip tftp source-interface <PORT or VLAN>

[kkinkaidcc]

Thanks! That did the trick.  I thought tftp would default to use the same interface as a ping but I guess not. 

[Leo Laohoo]

By default, TFTP uses a block-size of 512.  

The maximum size is "8192" and can make transferring a wee bit faster.

I, however, do not recommend increasing the TFTP block-size, for IOS-XE switches, to more than 1468 because of CSCvq01204.