At the access layer, the Adapter-FEX requires a FEX-enabled adapter on a server that connects to a parent device that supports virtualization of interfaces. The Adapter-FEX is supported on the following platforms:
*

The Cisco Unified Computing System (UCS) platform supports Adapter-FEX between UCS servers and the UCS Fabric Interconnect.

* The Adapter-FEX is supported on the Cisco Nexus 5500 Series platform and on the Cisco Nexus 2200 Fabric Extender that is connected to a Cisco Nexus 5500 Series parent device. This implementation works on a variety of FEX-capable adapters, including the Cisco UCS P81E virtual interface card (VIC) adapter for the UCS C-Series platform and third party adapters such as the Broadcom BCM57712 Convergence Network Interface Card, that implement the virtual network tag (VNTag) technology.
Reference:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/operations/adapt er_fex/513_n1_1/ops_adapter_fex/ops_using_adapter_fex.html