IEEE 802.1ah PBB

Provider backbone bridges (PBB), also known as MAC-in-MAC, provide support to carrier Ethernet networks. PBB defines a hierarchical network architecture and new frame formats that extend the functionality of provider bridges (IEEE802.1ad) for service providers that want to offer Layer 2 Ethernet services to their customers. With PBB, customer bridged (IEEE 802.1q) networks are aggregated into provider backbone bridge networks (IEEE 802.1ah networks).