Offers complete separation between provider and customer networks since there is no route exchange.
This is the same approach as overlay models (e.g. FR, ATM).
Carrier customer's layer 2 frames from one site to another transparently, and is hence independent of layer 3 protocols:
can carry IPv4, IPv6, IPX, DECnet, etc.
L2 Header – Label 1 – Label 2 – Optional Control Word – Tagged / Untagged Ethernet Payload
Label 1 is for the tunnel LSP
Label 2 is for the VC
Frames are sent between multiple customer sites within a VPN:
Builds full mesh of VCs (x2 because of uni-directionality of VCs) between member PEs in a VPN:
VPN ID = 32 bits (?)
PE routers learn MAC addresses just like normal switches, but only on received frames over VCs:
PE routers maintain layer 2 forwading table: VFI = Virtual Forwarding Instance.
PE routers do not have to run STP because of split horizon: