MPLS VPN Secure Architecture
Forwarding Within the SP network is based on labels, not on IP addresses
LSPs originate and terminate at the PE routers
LSPs are associated with logical ports on PEs
Logical ports on PEs are associated with VRFs, which are associated with VPNs at provisioning time
Inter-site LSPs are established based on the BGP Extended Community attributes and BGP sessions can be protected via MD5 authentication (RFC2385)
Injecting a packet into a VPN can only be done through a port on PE associated with that VPN