Are you sure you have the synchronization going fine between the active and failover? do you allow ping on the failover? Basically, when you reboot it switches to the failover unit but you need to make sure that the IP address on the failover unit is the IP you are pinging.
In your case, when you reboot, ping the the failover IP and it should respond to you!
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...