I have experience of openvpn, ciscos ipsec tunnels and alike but I wonder in what situation one would benefit from using a MPLS instead? If I understand it correctly, MPLS is L2 (but is sometimes referred to as layer 2.5, for unknown reasons to me), and if I understand the difference between the tun and tap drivers for OpenVPN, tap is L2 (ethernet).
I think MPLS in it self is not encrypted, so if we disregard the encryption of an openvpn tunnel - when would it be more suitable using a MPLS tunnel and when would it be more suitable using an Openvpn tunnel?
A secondary question too; I read on a forum somewhere that a proposed solution to connecting two datacentres servers (on one /24 network each using different carriers) was "have your DC transport VLAN" - How would this work? Over what protocol?