Cisco Simple GRE Tunnels (With IPSEC)
KB ID 0000951 Problem I’ve spent years setting up VPN tunnels between firewalls. The only time I’ve ever dealt with GRE is for letting VPN client software though firewalls. GRE’s job is to ‘encapsulate’ other protocols and transport those protocols inside a virtual point to point link. Below is the topology, I’m going to use. The tunnel will run form Router R1 to Router R3, once complete I should be...