GRE tunnel works between routers, not external devices.
I am trying to configure a GRE tunnel between two sites. In my configuration I have three Cisco routers. Router A and Router C are at the first site and are connected directly to each other - Router B is at the second site.
We can create the tunnel between Router A & B no problem. Running an show int tunnel 0 shows the link up. Router A can ping the interface on Router B and vice-versa. However I cannot ping the Router B interface from Router C. I feel like I am missing something basic but cannot identify it.
Relefant configuration and pings/traceroutes are available at the following URL.
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...