I do not believe that there is a way to do the transition from old ASA running 8.0 to new ASA running 9.1 without some downtime. But is is possible to minimize the downtime. I have recently done a transition like that and it was not an easy one. As you have discovered if you attempt to copy the old config to the new ASA it will reject as invalid syntax much of the access lists and all of the nat.
The easier way to do the transition is to have an ASA running the old code with the old config and to upgrade that ASA to 9.1. In this process the 9.1 code should read the config from startup and will do a conversion to the new syntax. I have done this going from 8.0 to 8.4 and see no reason why 9.1 would be different. You then only need to check the accuracy of the conversion. And then you can take the converted config and load it on the new ASA. In my recent conversion we did not have an extra ASA with old code, the new ASA does not support the old version, and the downtime to do this on the existing ASA was not acceptable. So I took the access lists and nat and did a manual translation from old to new. I loaded the modified config on the new ASA and did some checking. We then just switched connections from old ASA to new ASA and the downtime was minimal.
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...
[toc:faq]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 and UDP are I...