VXLAN support was added in ASA software release 9.4(1).
Reference: http://www.cisco.com/c/en/us/td/docs/security/asa/roadmap/asa_new_features.html
Therefore any ASA that is running 9.4(1) or later supports it.
That EXCLUDES the legacy 5500 series (5510, 5520, 5540 and 5580).
It INCLUDES any of the current models like 5506-X and higher, ASAv, ASA-SM and ASA logical device on a FirePOWER 4100 or 9300 series.
