VMware recommends several best practices when you boot your system from a software FCoE LUN.
Make sure that the host has access to the entire boot LUN. The boot LUN cannot be shared with other hosts even on shared storage.
If you use Intel 10 Gigabit Ethernet Controller (Niantec) with a Cisco switch, configure the switch port in the following way:
Enable the Spanning Tree Protocol (STP).
Turn off switchport trunk native vlan for the VLAN used for FCoE.