A VLL instance is a special type of VPLS deployment.
VLL provides point-to-point (p2p) connectivity between two access networks or endpoints. Typically, a VLL is used to connect two sites that are geographically apart.
The following figure depicts an enterprise VLL service.
CE1 and CE2 are the customer edge devices in geographically separate sites.
Pseudowire (PW) is a circuit emulation infrastructure that extends L2 connectivity from CE1 to CE2 by way of PE1 and PE2. The tunnel is typically a L3 tunnel on which a L2 circuit is emulated.