In both cases, when you re-attached the ASA to the network, were you able to ping out to the Internet from the ASA? It may have been an arp-cache updating issue. Did you also try clearing the IPSec sa's on the ASA to force a re-negotiation of the tunnel?
'clear crypto ipsec sa peer x.x.x.x'
If all else failed, I also would have just done a reload on the ASA and the upstream network device to be sure.
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...