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VIP Purple

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

  • LAN Switching and Routing
Everyone's tags (2)
1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Hello Rasika,

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

 

 

 

21 REPLIES
New Member

3850 Flash - Slow File Transfer rates

What tftp server you are using ? have you checked duplex negotiation issues ?

VIP Purple

Re: 3850 Flash - Slow File Transfer rates

Tried with multiple tftp servers like tftpd32 on windows 7, in builtin tftp on Macbook OSX & linux tftp server on network. I am sure ports are full duplex & 1G speeds

Also checked with SCP & speed was better (double the speed aroun 400KB/sec), still took around 10mins to copy the image.Still too slow from my perspective.

Rasika

Hall of Fame Super Gold

3850 Flash - Slow File Transfer rates

Try sticking the IOS into a flash drive and compare the outcomes.

VIP Purple

Re: 3850 Flash - Slow File Transfer rates

I will do this tomorrow & let you know Leo... already off for the day

Hall of Fame Super Gold

3850 Flash - Slow File Transfer rates

No problem.  Enjoy your day off. 

New Member

Re: 3850 Flash - Slow File Transfer rates

Just curious, after uploading did it do CRC check ?

VIP Purple

3850 Flash - Slow File Transfer rates

Hi Jonn,

Not too sure, no visible indication.

But the time observed is just copy the file to flash.

Regards

Rasika

VIP Purple

Re: 3850 Flash - Slow File Transfer rates

Hi Leo,

Here is the result of copying from USB to 3850 Flash, file transfer completed within 60s & this is what I expected via TFTP as well.

3850-1#copy usbflash0:cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin flash:

Destination filename [cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin]?

Copy in progress...CCCCC.....CCCCC

223734376 bytes copied in 60.180 secs (3717753 bytes/sec)

Here is the result I am getting with TFTP via directly connected PC. It is more than 20 minutes

3850-1#copy tftp://10.15.5.253/cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin flash:

Destination filename [cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin]?

Accessing tftp://10.15.5.253/cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin...

Loading cat3k_caa-universalk9.SPA.03.02.02.SE.150-1.EX2.bin from 10.15.5.253 (via Vlan999): !!!!!!!!    !!!!!

[OK - 223734376 bytes]

223734376 bytes copied in 1212.560 secs (184514 bytes/sec)

There is no duplex/collision issues as I can see laptop directly connected & negotiated to Full duplex/1000Mbps.

3850-1#sh int g1/0/1

GigabitEthernet1/0/1 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 58bf.eab6.5681 (bia 58bf.eab6.5681)

  MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX

Copy the same file to a 6500 flash & it took around 5 min, much faster than 3850/3750X

Why that much of drastic (>20 times) file transfer rate difference between locally attached device (USB) compare and Network server ? Cannot be writing speed to the 3850 flash, may be there is an efficient way of writing into disk when copy from locally attached USB ?

From the practical point of view copy an image from a network server would be the common use case & wonder if there is any way make this faster.

Thanks

Rasika

Hall of Fame Super Gold

Re: 3850 Flash - Slow File Transfer rates

(184514 bytes/sec)

Hmmmm ... that's pretty slow for over the network.

Something is slowing things down.

Do you have anti-virus enabled from the TFTP server? 

Let's do the basics first before you consider checking routing.

Is there drastic differences the way wrting to flash via TFTP

Compare the speed when you run HTTP.

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