I have set up a 1720 (with VPN module and isdn module) with IKE keep alives because the vpn terminates beyond the isdn termination.
The isdn address is negotiated and bound to a dialer interface
For testing I set the dialer list to ip any, so all worked well. Then I set the dialer list to list 101. This lists the ipsec protocol (esp) as interesting and IKE packets that have a source of 0.0.0.0
After a reload the router behaves as expected with the phase one exchange bringing up the line and then the isdn unbinding once real traffic stops.
The SA at the other end is deleted (no keep alives) and so we are set for the next time ;-) but there is no next time. The dialer neve sees another ike packet with a source of 0.0.0.0 unless the router reloads.
Fast switching does not work with VPN. The first packet goes through the tunnel, then the preceeding packets go through the cache to verify the destination.
Depending on what versions of code you are running, remove fast switching from the lan and the wan interface, no ip route-cache, and no ip mroute-cache. If you don't see it in the interface, it is on by default.
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...