The Cisco Identity Service Engine (ISE) is a NAC solution used for accessing the network. The version (while writing this post) is v2.4.
For a new implementation of Cisco ISE I had to re-image 2 SNS-3595 appliances with the latest software. This can be done in various ways;
Write the ISE iso to USB and boot / install from the USB flash-drive
Use the JAVA/HTML5 KVM option through the CICM interface
Hookup a USB DVD player with a dual-layer DVD containing the appropriate ISO file
The preferred option is the USB flash-drive, since it’s the fastest, but only if you are able to boot from USB….. After trying several USB flash drives with the tool recommended in the Cisco manual I gave up. No way that the Boot menu saw the USB flash drive. So after wasting several hours doing that I opted for the KVM install method.