Overview
IEEE 802.1ah Provider Backbone Bridge (PBB) is a MAC-in-MAC Layer 2 VPN technology. It interconnects multiple provider bridged networks to build a large-scale end-to-end Layer 2 provider bridged network.
PBB has the following advantages over QinQ:
Reduces the MAC address table size. In a PBB-enabled service provider network, only the edge devices maintain entries for customer MAC addresses. In a QinQ-enabled service provider network, all devices must maintain entries for customer MAC addresses.
Supports more than 16 million service instances. QinQ supports only a maximum of 4094 outer VLANs (service instances).
For more information about QinQ, see "Configuring QinQ."