4A0-105: Nokia Virtual Private LAN Services

A spoke SDP between PE-C and PE-D creates a hierarchical VPLS extension using only the new PE-C–PE-D connection. Traffic received on a spoke SDP can be forwarded to the existing mesh SDPs, whereas traffic received on a mesh SDP is not forwarded to other mesh SDPs. This preserves connectivity to the existing VPLS sites without adding full-mesh signaling or changing every existing PE.