:> Also, it looks like Cisco uses tftp to update the PIX. :> Will the existing settings be preserved...
:Yes, the existing configuration will stay intact. :The only changes will come when you "write memory" :for the first time with the new OS version. Then :there will usually be some new default values to :fixups and staff like that.
Not exactly...
When you boot with the new PIX software version, it will start out with certain new defaults. It will then parse your existing startup configuration; it will see there some commands that are in a slightly different form now, and it will automatically convert them to the new form in the running configuration. The changes won't get locked into the startup configuration until you "write memory", but if you don't "write memory" then all that happens is that each time you boot or reload, the PIX re-parses the old startup configuration, sees the old commands, and converts them into the new forms for use by the running configuration. Whether you "write memory" or not is thus "a difference that makes no difference".
There isn't very much that gets converted between 6.3(1) and
6.3(4). The SIP fixup is the only thing I can think of at the moment.