How is ASA nat-ed through router? How many public ip's do you have?
If there is only one public ip that you should do port mapping and map UDP ports 500 and 4500 from asa to public ip. If there are more then one public ip then you can do one to one nat and then it should work if there are no access-lists.
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...