S network. This allows a customer location to have direct visibility to every other location belonging to that customer. Unique MPLS labels are used to segment one customer's traffic from another's and to segment one service from another. This segmentation allows a customer acquire a bundle of services from its provider, each of which is tailored for the end application. For example, a customer's bundle could comprise VoIP, Internet access, and maybe two or more VPN services. The first VPN service could be to provide broad data connectivity between all corporate locations, accessible to all employees. The second VPN service could be restricted to some financial transactions conducted between a subset of locations. Each of these services would be uniquely configured over VPLS, thus allowing them to have unique quality and security attributes. Logical Bridge Point-to-Point Pseudo-wires MPLS Backbone Figure 9.26 VPLS VPLS provides logical LAN bridging or switching functions over a packet- switched network. The provider edge performs virtual bridging or switching for LAN-attached customer edge nodes. VPLS supports both point-to-multipoint and multipoint-to-multipoint service using PWE3. PWE3 specifies the encapsulation, transport, control, management, interworking, and security of services emulated over packet-switched networks. The benefits to carriers of combining Ethernet and MPLS are numerous. Carri- ers immediately benefit from the lower capital expenditure required for deploying Ethernet infrastructure. However, a simple Ethernet switched network has limita- tions on service scalability due to VLAN ID restrictions as well as limitations on reliability (e.g., Spanning Tree Protocol does not scale well). These limitations are solved by MPLS, which offers a portfolio of solutions that provide massive scalabil- ity and multiple reliability options and also bring other benefits. For example, MPLS's dynamic signaling is instrumental in providing quicker changes and recon- figurations of service. Its traffic engineeri