e The development of PBB-TE is mandating further enhancements in the existing control plane. The control plane of PBB and PBB-TE is under development under the guidance of IEEE 802. laq WG. Ethernet control planes populate the Forwarding Information base. Many deployments of Ethernet do not use the control plane (spanning tree/learning) and instead use configuration (no learning). To add another control plane it looks like the industry is trying to use the configured option to address PBB-TE requirements as shown in Figure 7.20. Next Generation Mobile Communications Ecosystem 802.1D 802.1Q 802.1ad 802.1ah 802.1Qay (MAC Bridges) (VLAN Tagging) (Provider Bridges) (PBB) (PBB-TE) Payload Payload Payload Payload Payload C-VID C-VID C-VID S-VID S-VID S-VID I-SID I-SID SA: Source MAC Address DA: Destination MAC Address B-VID B-VID VID: VLAN ID C-VID: Customer VID S-VID: Service VID I-SID: 24 bit Service ID B-VID: Backbone VID B-SA: Backbone SA B-DA: Backbone DA T-IID T-IID: TE-Service Instance Identifier T-SA: TE-Service SA T-SA: TE-Service DA Figure 7.19 Ethernet frame structure evolution towards Carrier Ethernet PLSB (Provider Link State Bridging) [34], a proposal from Nortel, adds a control plane to the PBB data plane in order to extend the techniques for manipulation of Ethernet bridges for unicast paths pioneered by PBB-TE. PLSB combines Intermediate System to Intermediate System (IS-IS) [36], PBB, PBB-TE, and a data plane enhancement in the form of a data plane ingress check to produce an Ethernet mesh solution with a layer 2 distributed control plane for a provider backbone bridged network. PLSB is currently being proposed for standardization to the IEEE 802 community as part of the 802.1aq (Shortest Path Bridging) project. This project addresses a carrier-scale ELAN (Ethernet LAN) infrastructure, with a target of 1000 bridges. PLSB enhances PBB with the addition of a layer 2 routing system and loop mitigation in order to produce a better spanning tree for PBB, better in the sense that all trees are shortest path