Working with the Cisco IOS File System, Configuration Files, and Software Images. This appendix describes how to manipulate the Catalyst 3750 switch flash file.
The last way I want to upgrade firmware is through the Serial port, even changing the baud rate to the highest possible takes forever to transfer an image, what I like to do is either hook my laptop via Ethernet to the switch directly and give the switch and laptop each an IP address on the same network so they I can transfer an image via TFTP, or give the switch an IP on my network (behind a firewall of course) and transfer the image via TFTP that way. Either way will work as long as the switch and your computer running a TFTP server can ping this will work.
![Cisco 3750 switch ios upgrade guide Cisco 3750 switch ios upgrade guide](/uploads/1/2/5/8/125871666/148888996.jpg)
You will need to have a TFTP server installed on your laptop/workstation any TFTP server you know how to configure and use will work.
Once the TFTP server on your computer is running and you have the firmware you wish to load available to the TFTP service, go on the switch issue the following command
Note you can delete the existing image prior to the reboot and cause the switch to be forced to use the new firmware, although if there is an issue with the firmware you uploaded and it cant boot, it will have nothing to revert back to. From what I have experienced the majority of the time there is space on flash for 2 images at a time so as long as you remove the old firmware after you have confirmed you can boot to the new firmware you should be fine.