PBB-TE (802.1ay) defines methods for defining Backbone Tunnels in Ethernet networks. It includes VLAN tagging, Service Bridge Tagging, and Ethernet tunneling in Ethernet frames.
IEEE Standard for Local and Metropolitan Area Networks - Virtual Bridged Local Area Networks
Amendment to IEEE 802.1Q-2005. IEEE Standard for Local and metropolitan area networks - Virtual Bridged Local Area Networks - Amendment 4: Provider Bridges
Provider Backbone Bridge (PBB)
Provider Backbone Bridge - Traffic Engineering (PBB-TE)
LAN/MAN CSMA/CD Access Method