I am running several VPNs from my HA router with different appliances. We have issues with this Fortigate 400A, tunnel, but traffic passes only sporadically (tunnel never drops). For example sometimes icmp responds through the tunnel and sometimes it just times out. Need to know any know issue that could prevent traffic from crossing the tunnel.
The problem will be due to mismatch IKE keepalives. By default IKE keepalive's on cisco devices is 86400 seconds. Check the keepalive's at the Fortigate and configure it accordingly. Following links may help you
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...