Cisco has this week released NX-OS 5.1(3)N1(1) for Nexus 5000 Series switches. See the release notes for more information, and there really is lots of information: http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/sw/release/notes/Rel_5_1_3_N1_1/Nexus5000_Release_Notes_5_1_3_N1.html Note: The Dual-layer vPC I talked about is called Enhanced vPC (EvPC) in the release notes.