Since VPLS emulates a LAN, full mesh connectivity is required. There are two methods for full mesh establishment for VPLS: using Border Gateway Protocol (BGP) and using Label Distribution Protocol (LDP). The "control plane" is the means by which provider edge (PE) routers communicate for auto-discovery and signalling. Auto-discovery refers to the process of finding other PE routers participating in the same VPN or VPLS. Signalling is the process of establishing pseudowires (PW). The PWs constitute the "data plane", whereby PEs send customer VPN/VPLS traffic to other PEs.