udo-wire tunnels, customers' sites can be connected via point-to-point circuits as if they were using their own private leased lines (see Figure 9.25). VPWS VPNs support traffic types such as Ethernet, ATM, Frame Relay, SDH/SONET, and TDM. VPWS provides a mesh of point-to-point customer edge-to-customer edge Layer 2 connections over a packet-switched network. The provider edge does the mapping between the attachment circuit and the pseudo-wire. VPWS is seen largely as an appropriate approach for point-to-point connec- tion-oriented services, such as ATM, Frame Relay, and point-to-point Ethernet. For multipoint-to-multipoint connectionless services such as Ethernet and VLANs, VPLS is required. VPLS A number of vendors have adopted the VPLS approach, and deployments of VPLS are mushrooming worldwide. VPLS is a growing solution for providing Ethernet services. It combines the benefits of Ethernet and MPLS for both custom- ers and carriers. Pseudo-wires Provider Backbone Attachment Circuits Figure 9.25 VPWS Chapter 9 IP Services VPLS offers at Layer 2 what IP VPNs offer at Layer 3: a service with multipoint connectivity (see Figure 9.26). The main difference is the interface used between the customer edge equipment and the provider edge equipment. With IP VPNs, cus- tomer edge equipment is IP routers, whereas with VPLS, it can be an Ethernet bridge, a switch, a hub, or a router, allowing non-IP traffic as well as IP traffic to be exchanged between sites. Apart from this essential difference, MPLS Layer 2 VPNs and Layer 3 VPN-based approaches are very similar in other areas. Both share the same common MPLS protocols and the underlying IP/MPLS infrastructure. In the past, these services were most commonly delivered on TDM, Frame Relay, and ATM networks. VPLS is one of the most innovative and easily manageable ways of pro- viding Ethernet MPLS VPNs. Each customer location is attached to a node on the MPLS network. For each customer or VPN, a full mesh of logical point-to-point connections is set up over the backbone MPL