Can I configure the way if connection to site a or b failed the traffic will route to site C. This senario will occur in the event a complete loss to a site and active/ passive firewalls does work in site A or B.
You guys don't have some kind of routing protocol in place? I have worked at couple of different places where we had two VPN's setup between sites and we used EIGRP. So if one would go down EIGRP would send over the other VPN. Ofcourse you'll need to do GRE, VTI to configure EIGRP accross the VPN.
If I understand correctly, you have Primary mode of connection as MPLS across sites A, B & C. And looking for VPN over Internet as back up solution.
I would suggets you to go with Cisco DMVPN rather GRE/IPsec.(Though GRE/IPsec works fine) You can use dynamic routing protocol such as EIGRP/OSPF over DMVPN as your backup solution when primary is down.
Alternatively, if your application is hosted in a Primary site, you could provide a Remote Access VPN solution (e.g., Cisco Anyconnect SSL VPN ) with RSA two factor authentication for users to dial-in
I know the basics for Cisco routers and switches but what I want to know is, if I set up VTP on a switch, is there a way to send it through routers to other switches? This will probably end up more hassle than gain, but it's interesting and cool to p...