Switch# show boot Look for the line BOOT path-list . It currently points to your old IOS. Enter global configuration mode and set the new boot variable.

Do not interrupt the copy process. While USB is fast, cutting power or pressing Ctrl+C during the write process can corrupt the flash memory. Phase 3: Managing the Boot Variable Simply copying the file is not enough. The switch needs to be told specifically which file to load when it boots. If you do not update the boot variable, the switch will attempt to load the old IOS (if still present) or fail to boot. Step 1: Check Current Boot Settings First, see what the switch is currently set to boot:

Switch# copy usbflash0:cat3750e-universalk9-mz.150-2.SE10.bin flash: (Note: Replace cat3750e-universalk9-mz.150-2.SE10.bin with the exact filename of your specific IOS image. Cisco filenames can be long; using the TAB key for auto-completion is highly recommended.)

Switch# conf t Switch(config)# boot system flash:cat3750e-universalk9-mz.150-2.SE10.bin Switch(config)# end *Tip: If you have multiple IOS files in flash and you want the switch to attempt them in order, you can enter multiple boot system commands. The switch processes them sequentially. However, for a clean upgrade, it is best to have only one `

Switch> enable Switch# show version Look for the "cisco WS-C3750X" line and check the memory stats. Next, check your flash storage:

Traditionally, engineers upgraded IOS images using TFTP (Trivial File Transfer Protocol). However, TFTP is notoriously slow, prone to timing out over WAN links, and requires setting up a server. For the modern engineer, there is a vastly superior method: using the built-in USB port on the 3750-X.

Run the following commands: