2960. What is the cause of this latency? (pcap + CLI pict attached)

[jmaxwellUSAF]

Hello.

Please see attached picture.

What is the most likely cause of this tftp download symptom?

Thank you.

[balaji.bandi · Accepted solution]

what is switch IP and TFTP IP address ?

you can try increasing blocksize - if your IOS support.

ip tftp blocksize 8192

Also try using tftp source interface.

Note : also check any CoPP policies on the switch.

can you also post ping oputput repeat 100 or 500 count see is that connectivity good ?

[jmaxwellUSAF]

this looks helpful..

Solved: TFTP Speed Increase - Cisco Community

[Joseph W. Doherty]

"What is the most likely cause of this tftp download symptom?"

Unsure there's enough information to say.

However, if I'm reading your PCAP stats correctly, looks to be about 30 ms RTT.(?)

What's the ping time between the 2960 and the ftfp server?

Have (or can) you use/try a FTP transfer?

[jmaxwellUSAF]

Quick question please-- I'm 98% sure there is ftp config issue on server, but please confirm...

Does ftp protocol need to be explicitly configured for ftp file transfers on 2960X switch?

Ping results...

2960X#ping (!! tftp server !!) repeat 500
Type escape sequence to abort.
Sending 500, 100-byte ICMP Echos to (!! tftp server !!), timeout is 2 seconds:
Success rate is 100 percent (500/500), round-trip min/avg/max = 20/38/154 ms

Does this speed seem normal?

Thank you.

[Joseph W. Doherty]

"Does ftp protocol need to be explicitly configured for ftp file transfers on 2960X switch?"

As a FTP (or tftp or RCP) client, it normally does not need additional configuration.  (Setting up FTP/tftp/RCP as a server, on a Cisco device, does, though.)

(Oh, forgot to mention, FTP servers might require logon validation.)

"Does this speed seem normal?"

Without knowing anything about the topology or its usage, cannot really say.

However, we do see your average ping RTT is about twice the minimum and your maximum almost eight time the minimum, i.e. it's variable, which often isn't totally unusual for best-effort networks (i.e. no QoS - configured to try to achieve more consistent performance).

One positive, is you didn't have any ping drops.

You might also try pinging 1500 and 64 KB sizes, and see what those results are, as the default uses minimum packet size.

[balaji.bandi]

Success rate is 100 percent (500/500), round-trip min/avg/max = 20/38/154 ms

if this is in the Lan - i believe average is ok, but sometime it gone up 154ms, so i take network should be busy when you doing this ping.

But if you increase the block size is the resolve the issue ? or still having issue of transfer ?

yes you can use FTP - there is no requirement, as long as you do not have any firewall between to allow the traffic.

Note : if the switch has different routes , worth configured source interface to reach TFTP or FTP Server.

[jmaxwellUSAF]

Thank you for your replies. They have definitely help me understand and troubleshoot this issue. The real world is forcing me to cease investigation on this.

My solution is to use FTP so, at least, I can better troubleshoot tcp conns, and the reliable nature of the protocol will better ensure file integrity.

Thank you.

[Joseph W. Doherty]

"The real world is forcing me to cease investigation on this."

Laugh - been there, done that, too.  However, if there's a real issue you have not identified, even if you have a workable alternative, such a real issue may arise later.  I.e. if possible, when pressed, give such situations low priority, to resolve, but don't ignore them.

". . . is to use FTP . . . the reliable nature of the protocol will better ensure file integrity."

Actually, FTP is unlikely to be better than tftp, in this regard (as tftp, itself, does what TCP does for FTP).  The most common "improvement" you'll see, especially when end-to-end latency is higher due to physical distance, is a faster transfer rate.