Cisco Verizon Nortel Cisco Provider Backbone Bridge (PBB) functionality, under standardization in IEEE 802.1ah, can be employed to enhance the scalability of H- VPLS with MPLS access. This document describes how PBB technology can be used in H-VPLS with MPLS access networks to improve the scalability of customer MAC addresses and number of service instances that can be supported. The document also describes the migration mechanisms and scenarios by which PBB functionality can be incorporated into H-VPLS with existing MPLS access.