Fabric binding ensures that switches configured in the fabric binding database are permitted to connect to the switch. If a switch tries to join the fabric, and that switch is not in the fabric binding database, access is denied. Fabric binding is configured on a per-VSAN basis.
From Cisco, “This feature helps prevent unauthorized switches from joining the fabric or disrupting current fabric operations. It uses the Exchange Fabric Membership Data (EFMD) protocol to ensure that the list of authorized switches is identical in all switches in the fabric.”
This is very similar to Port Security, except Fabric Binding is for switches only (not devices). Switches bind to the fabric instead of interfaces like in Port Security. Additionally, Fabric Binding is manually configured on each switch, it cannot be distributed through CFS.
More information can be found here:
1. Enable the fabric binding feature
2. Configure a list of sWWNs and their corresponding domain IDs for devices permitted in the fabric
3. Active the fabric binding database
4. Copy the fabric binding database to the fabric binding config database