Deliver configs via TFTP, blocksize problem, help!

[Alisdair Mckeand]

Hello

We are about to rollout 500+ Cat3K Switches and we are trying to deliver the new configs via TFTP but it’s not working and I think we have worked out why, in IOS XE 16.x.x the block size appears to have changed, how do we work around this without manually getting involved with console cable which will render the process we are implementing null and void? Below is the error and my testing that shows out of the box the block size is 8192, could it be as simple as looking at a newer TFTP service?

j1cat3650-testsw03#ping lens

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to xx.xx.xx.xx, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

j1cat3650-testsw03#copy tftp: flash:

Address or name of remote host [x.x.x.x]? lens

Source filename [j2cat3560-a2-confg]?

Destination filename [j2cat3560-a2-confg]?

Accessing tftp://lens/j2cat3560-a2-confg...

%Error opening tftp://lens/j2cat3560-a2-confg (Timed out)

j1cat3650-testsw03#sh run all | in tftp

ip tftp blocksize 8192

j1cat3650-testsw03#conf t

j1cat3650-testsw03(config)#ip tftp blocksize 1400

j1cat3650-testsw03#copy tftp: flash:  

Address or name of remote host [lens]?

Source filename [j2cat3560-a2-confg]?

Destination filename [j2cat3560-a2-confg]?

Accessing tftp://lens/j2cat3560-a2-confg...

Loading j2cat3560-a2-confg from x.x.x.x (via Vlan2): !

[OK - 31412 bytes]

[aradford]

interesting.  We made this change due to poor performance when downloading images.  What tftp server are you using?

[Alisdair Mckeand]

Hi Adam

Thanks for the quick reply

Yeah that is understandable as a 3K IOS-XE image would take well over 20 minutes at the old 512 block size but only a few minutes at 8192, the Customer is using TFTPD64, I have done some tests this morning using TFTPD32 Client on my Laptop and accessing the config on the Customers TFTPD64 Server and tried all available block sizes but none of them work, it only transfers the test.txt file when I select "Default" on the blocksize dropdown box under the "Tftp Client" tab, on the TFTPD64 side the console output unfortunately doesn't state the blocksize of what "Default" is like it does when trying say 512, 1024, 8192, etc

Is a strange one as we were hoping to push out and deliver all 500 configs to the 3650 and 3850 Switches via TFTP rather than manually uploading them all to the PNP App

Cheers

Ali

[aradford]

I wrote a python script to take all the config files in a directory and upload them using the REST API.

See the PnPSync script.

https://communities.cisco.com/community/developer/dna/blog/2017/02/24/next-generation-network-deployment-plug-and-play-part8

That would give you HTTPS download rather than tftp.

Strange that the TFTP64 server is not working correctly. Must be some issue with block negotiation.

Adam

[Alisdair Mckeand]

Thank you I will take a read of this post as this might be a good work around in having to use TFTP

On the side line we are also going to test SolarWinds TFTP Server as I believe it could be a negotiation bug or alike

Thank you as always!