The Cisco ASA 8.3 is quite a major release despite the minor version number update. One of the major feature overhaul is the NAT. NAT and statics are no longer bound to an interface. It has moved towards an network object based approach. This opens the possibility of enabling global NAT statements. However, I’m pretty certain that as part of such a large change, more memory is consumed and Cisco has bumped up the memory requirements for almost each model of the ASA.
Table 1. Memory Requirements for Cisco ASA Software Release 8.3
Two models that I’m familiar with is the ASA 5505 (Security Plus license) and ASA5520. Despite the Cisco’s requirements for the ASA 5505 is only 512Mb, it was not picky on the RAM that was tested with. In fact, we stuck in a regular desktop DDR 1G ram into the ASA5505 and it took it, no questions asked. Similarly the ASA5520 took 4 x 512MB of regular DDR memory without a problem.
Disclaimer: I’m not recommending anyone to use non-Cisco RAM. Anyone who is upgrading their ram on any ASA should consult Cisco documentation and is liable for their own actions.