The "upgrade" file and System Image files will install the same files on the sensor.
There are 2 main differences:
The 1st difference is that the "upgrade" will convert your current configuration to work with the new version while a System Image will reformat the flash/disk and all previous configuration will be lost.
The 2nd difference is how they are installed. The "upgrade" file is installed directly onto a running sensor using the running IPS software. Either through the IPS CLI, IDM, IME, CSM, or an auto upgrade.
The System Images, however, rely on an alternate method. The Appliances use ROMMON, the AIP-SSM modules use the hw-module command of the ASA, the IDSM-2 uses a Maintenance Partition, the AIM-IPS uses a bootloader. Each of the different methods requires a different type of image, and so each System Image is specific to the platform, but almost all of the System Images contain and install the same files as the upgrades.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...