You could be looking at some recursive routing throug the GRE interface, so the second it comes up it will try to put the GRE packets through the GRE tunnel, this creating a loop. Are you using a dynamic routing protocol to get network info over the GRE tunnel or a static route if so, how is it setup ?
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...