Increase the TFTP File Transfer Rate (3850 Example)

 

1. Introduction

 This document describes how the Cisco IOS® image size increases when you upload an image to a switch.

 2. Objective

This size increase results in a longer transfer time. The later release on the Cisco Catalyst 3850 is 245MB in size and can take up to 30 minutes to 1 hours to TFTP to the switch. The configuration described in this document can be used to speed up the transfer time.

 

3. TEST and Configuration Results

By default, the Catalyst 3850 uses a TFTP block size value of 512, which is the lowest possible value. This default setting is used in order to ensure interoperability with legacy TFTP servers.

3850(config)#ip tftp blocksize ?

  <512-8192>  blocksize value

In the Cisco IOS-XE 3.3.2 and earlier versions, you must manually change the block size in the global configuration to speed up the transfer process.

Note: This example shows a transfer comparison when you use the default block size of 512K versus a transfer of 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 is equal to 24 minutes). 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 executed 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 is transferred in two minutes with the new block size value.

 

COMMAND : ip tftp blocksize 8192