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VIP Mentor

3850 Flash - Slow File Transfer rates

During a recent 3850 switch upgrade  I noticed I got very slow data rate (~200 KB/sec & took around 24 min) when copying new image to 3850 Flash.

cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin (213MB)        

Since it was from a Network TFTP server, I tried it again with local TFTP from a PC directly connected to 3850 and still got same low file transfer rates.

Did anyone else notice this ? What could be the cause for this slow file transfer rates ?

Rasika

22 REPLIES 22
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Hall of Fame Community Legend

Thanks Rasika.

Nothing suspicious from your output (bummer!).

Can I ask you to do another test ...

This time, you two switches in a stack but minus the rest of your network.  Plug your client directly to the stack of switch and check if there is improvement(s) when you do TFTP copy.

I'm not trying to determine if something in the network is slowing you down. 

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VIP Expert

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

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In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Can't say for sure for a 3850, but in general, often rewritable flash memory designated to be used like ROM, isn't designed for high speed write access.

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Hi Joseph,

May be true, as posted above , when I copy from USB to 3850 flash, it copied within 1min. But across network (even directly connected PC TFTP), alll the time it is taking more than 20 min.

Tried to copy to 6500 flash, it is much faster (~5 min)

Is there drastic differences the way wrting to flash via TFTP & via locally attached USB ?

Rasika

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Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Rasika, yes I saw your later posting with the USB results.  Certainly quite a difference!  Assuming there's not something wrong with the 3850 (considering how new they still are, that might be a possibility), the only other usual causes for slow TFTP transfers are latency (as TFTP usually only sends one packet per ACK) or high loss/drop rate.

If the TFTP server is directly connected to the 3850, you're 100% positive interface shows no errors and both sides are in agreement about duplex?

Have your tried any other TFTP servers (several free ones are available for PCs) or a FTP server; just to see if you obtain the same results?

[edit]

PS:

Laugh - should have read more of the new postings - you have done additional testing - also like Leo, again, there might be something wrong (i.e. possible bug).

PPS:

Oh, and if you want to try another test, assuming you have enough flash to hold two copies of the file, you can copy the file from flash to flash using a different name.

[edit2]

Is there drastic differences the way wrting to flash via TFTP & via locally attached USB ?

There can be, as the network is eliminated as a factor.  But for a TFTP server locally attached, wouldn't expect a significant difference.

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HI Josef I am also facing same issue of high cpu utilization.

Highlighted
Cisco Employee

Hello Rasika,

By default, the Catalyst 3850 uses a tftp block size value of 512, which is the lowest possible value.  The reasoning behind this default value is to ensure interoperability with legacy tftp servers. 

 

3850(config)#ip tftp blocksize ?
  <512-8192>  blocksize value

 

For IOS-XE version 3.3.2 and below, you will have to manually change the block size in the global configuration to speed up the transfer process.  The example below is a transfer comparison when using the default block size of 512K versus a transfer using the maximum block size value of 8192K. 

 

3850#copy tftp flash:
Address [172.16.108.26]?
Source filename [IOS/3850/cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin
Destination filename [cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin]?
Accessing tftp://*****@172.16.108.26/cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin...
Loading cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin from 172.16.108.26 (via Vlan1): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[OK - 257243236 bytes]
 
257243236 bytes copied in 1416.360 secs (181623 bytes/sec)

 

The results show that the 245mb .bin file was transferred in 1416.360 seconds, which equals almost 24 minutes.  I will now adjust the block size value to the maximum allowed value of 8192.

 

3850#config t
3850(config)#ip tftp blocksize 8192
3850(config)#end

 

The same transfer is now run again.

 

3850#copy tftp flash:
Address [172.16.108.26]?
Source filename [IOS/3850/cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin
Destination filename [cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin]?
Accessing tftp://*****@172.16.108.26/cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin...
Loading cat3k_caa-universalk9.SPA.03.03.02.SE.150-1.EZ2.bin from 172.16.108.26 (via Vlan1):
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[OK - 257243236 bytes]
 
257243236 bytes copied in 124.100 secs (2072871 bytes/sec)

 

The results are clearly better.   The same file was transferred in just over two minutes with the new block size value.

 

Hope that helps!!

 

Luke

 

 

 

View solution in original post

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Hi Luke,

Thank you very much for the tip & providing us correct answer.

Regards

Rasika

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THANK YOU Luke .. This helped a lot !!!!

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