Re: VPN Concentrator to Cisco 1721 router, Lan-2-Lan Ipsec tunne
The vpn concentrator will accept a tunnel to any IETF compliant device, which means that you can use PIX, Routers, Windows Machines and any other 3rd party device as long as the are standard compliant.
As for the version you would need to use at least a security version, check the feature navigator:
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...