I have done some search and I found that there is two series of cisco firewalls : Cisco ASA 5500 series and Cisco PIX 500 series firewalls.
Do all Cisco Firewalls support IPSec configuration?
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IPSEC is supported on all of the PIX and ASA models. Your image and license will determine which types of encryption you can use.
The PIX series is no longer being produced. It is fairly rare to see them in any production system at this point. There are two series of ASAs currently. You have the X and non X series. The X series is the newest and introduces faster hardware and support for FirePOWER services. (Cisco purchased Sourcefire and integrated this in to their newer ASA products) Newer versions of the ASA software also support SMP for the RX and TX Rings. This allows multiple processor cores to service the rings, improving overall system performance.