Nexus 5k can't send config to tftp server

[jbankstonps]

fairly new to Nexus and working on a 5596, learning my way around nicely. Time came to save the config to a tftp server and found an odd problem - the nexus can create the .txt file but times out transferring the body and leaves a zero byte file. Simple config, one vlan and one Lo0 intf which the nexus sources tftp from Lo0. The firewall the nexus connects to allows all Nexus traffic, this is a simple lab setup. Routes are in place, pings are fine, seemingly nothing wrong to stop tftp from working.

Scouring the internet hasn't been useful, two different tftp servers in use on two different OS, same issue so I know the issue is in the Nexus. System version: 7.3(4)N1(1)

Appreciate any thoughts.

-Jeff

[MHM Cisco World]

ip tftp source-interface x
 add source-interface that use to connect to tftp after you check that the IP you add is reachable from TFTP server.

[balaji.bandi]

what command syntax you using  , by default it used vrf default

can you post command used and errror you getting ?

[Richard Burts]

Are there any log messages generated on the tftp server when you attempt this? If a zero byte file is created on the server then the request from your Nexus is getting to the server and so IP connectivity is not an issue. I am wondering about the possibility of something like permissions issues on the server.

[jbankstonps]

so I just added a 3750X as a downstream switch to the Nexus, and it works flawlessly to the tftp server, on same subnet as the mgmt vlan on the Nexus

Nexus output below, note that all other features and functions on the Nexus works just fine.

PSCore5596# copy running-config tftp:
Enter destination filename: [PSCore5596-running-config] Nexus5596.txt
Enter vrf (If no input, current vrf 'default' is considered):
Enter hostname for the tftp server: 10.10.40.21
Trying to connect to tftp server......
Using IP address of interface loopback0
Connection to Server Established.
TFTP put operation failed:Connection timed out
PSCore5596#

strangest thing I've ever seen.

-Jeff

[MHM Cisco World]

ping tftp source lo
check the reachable. 

[Richard Burts]

Jeff

Thanks for the additional Information. It is interesting that a 3750X connected through the Nexus works. But that does not shed much light on why the Nexus does not work.

The output that you post is somewhat helpful. It does confirm that it is using the IP address from the loopback, which has been one of the suggestions. And this message

Connection to Server Established.

does confirm that the connection was established. So IP connectivity is not the issue. We have eliminated a couple of possibles causes of the problem, but we still do not know what the problem is. In addition to wanting to know if there are any log messages on the server, I wonder if debug for tftp might shed some light on what is going on.

[jbankstonps · Accepted solution]

found it...... another oddity with Nexus I am learning.

Nexus demands that tftp sources either from mgmt0 or a Loopback. I'm used to IOS/XE where I can state any physical, logical, or other interface to source traffic from. The Nexus has Lo0 defined, and a mgmt0 OOB interface, and Test60 vlan for use. There was a missing route in the upstream device to say

for Loopback0 point to Vlan60 as the next hop on the Nexus

once that was put in, magic stuff. Imagine that........

[MHM Cisco World]

I mention before not one time but twice check reachability, 
but anyway 
glad your issue is solve 
good luck friend

[jbankstonps]

I don't normally reply to snide comments like yours, but this is important because I have been in and around Cisco route/switch since 1996 which is why this problem baffled me so much. Recall in my original post that I said everything about the Nexus config is working as expected except the tftp problem, thus "reachability" isn't a top thought at the time as ntp, ssh, syslog, etc all are working fine. Especially since the log server indicated a session was established again shows "reachability" is good.

As I clearly pointed out that I am a Nexus rookie (not a Cisco rookie), and spending time working out these new and learning issues to gain a better understanding of a Cisco technology I had never touched before, would you please consider in the future to not be so chastizing and abrasive with comments like that?

Consider that there must be a host of networking youngsters lurking out there hesitant to post here so as to not feel the way your post makes it seem to participate in this community when one admits to being a rookie at a technology, yet yearning to learn it from the Pro's here.

Richard Burts exemplifies that Pro standard we all love to see here in Cisco Communities, thank you Richard.

[MHM Cisco World]

First sorry IF I in any way disturbance you.
 
you mention 
ntp, ssh, syslog work correctly but only TFTP, may be this is because TFTP server in different subnet than other Servers.
and I read your posts, I suggest to check reachable why ? because one of your post
TFTP put operation failed:Connection timed out

so even if nexus can reach the TFTP the TFTP return back can not reach nexus. 
and that why I suggest using ping with source. 

sorry again 
and good luck Friend. 

[Richard Burts]

Jeff

This has been a very interesting discussion and I have several things that I want to say about it:

1) You are welcome. I am glad that my suggestions were helpful.

2) Congratulations to you for finding and solving the problem. And thanks for sharing the solution with us.

3) It is interesting that the problem turns out to be a missing route. I said that the connection established message indicated that IP connectivity was not an issue. And that was a big mistake on my part. IP connectivity is a two way thing. The request must get to the destination and a response must get back to the source. In this case the connection established does indicate that the request was received. But the response did not get back to the source. My bad and I acknowledge it.

4) I am sorry that you felt that the comments from MHM were snide. In fact he was on the right track. If we had done the ping to the server earlier in the process it would have shown that there was an IP connectivity problem.

[jbankstonps]

your insights led to the solution, I appreciate you!!

[Darian O'Dirling - TCE]

Hi Everyone,

If anyone is looking for a good video resource on file transfer on nexus this video provides a look at the steps and best practices of file transfer on a Nexus data center switch. Utilizing the information shared in the video the most efficient transfer speeds to and from a Nexus switch can be obtained.

https://www.youtube.com/watch?v=jBn1yy1uBps