Enabling FCoE on a Nexus swich is pretty simple:

feature fcoe

What’s not all that well documented is that uses a temporary 120 day license. After the 120 days the switch disables FCoE. That is a very bad thing, especially when the switch is providing the storage backbone for a vSphere cluster running around 200VMs.

To properly license FCoE a license number must be registered on Cisco’s website. This generates a license file that gets uploaded to the switch. http://www.cisco.com/en/US/docs/switches/datacenter/sw/nx-os/licensing/guide/Cisco_NX-OS_Licensing_Guide_chapter1.html#task_24958