Cisco PIX Security Appliance customers are encouraged to migrate to Cisco ASA 5500 Series Adaptive Security Appliances. Licenses mapped here are for the Cisco ASA 5500 Series, and they provide a function similar to the Cisco PIX Security Appliance licenses they refer to. Please note that Cisco ASA 5500 Series appliances have a simpler base licensing structure than Cisco PIX Security Appliances. Features activated with UR/FO/FO-AA licenses on Cisco PIX 525 and 535 Appliances, are included with the base models of Cisco ASA 5520, 5540, 5550, and 5580 Adaptive Security Appliances. Features activated with UR/FO/FO-AA licenses on Cisco PIX 515E Security Appliances, are activated by the Security Plus license on Cisco ASA 5510 Adaptive Security Appliances. The Security Plus license on Cisco ASA 5510 also activates other features such as SSL/IPsec VPN clustering and load balancing, in addition to unlocking Gigabit Ethernet support on two of the embedded ports of the Cisco ASA 5510.