To prevent data corruption due to cross fabric communication in an FCoE environment, the network engineer must apply the configuration Switch(config)#fcoe fcmap 0e,fc,2a to the Cisco Nexus Unified Switches. This configuration sets the FCoE MAC address prefix (fcmap) to a custom value of 0e,fc,2a, which is different from the default value of 0e,fc,00. The fcmap is used to identify the FCoE traffic and map it to the corresponding Fibre Channel ID (FCID). By using a custom fcmap, the network engineer can avoid the possibility of FCID conflicts or overlaps between different FCoE fabrics, which can cause data corruption or loss. The custom fcmap must be configured on all the switches in the same FCoE fabric, and must be unique across different FCoE fabrics. References :=
* Implementing and Operating Cisco Data Center Core Technologies (DCCOR) v1.2, Module 7: Data Center Storage Connectivity, Lesson 7.4: FCoE Protocol
* Cisco Nexus 9000 Series NX-OS FCoE Configuration Guide, Release 9.3(x), Chapter: Configuring FCoE, Section: Configuring the FCoE MAC Address Prefix
