es to seamlessly communicate. To accomplish this goal, most carriers are planning to simplify their network infra- structures over a common MPLS core and introduce MPLS-based services. Table 9.2 Summary of RFC 2547 and Virtual Router VPNs Characteristic RFC 2547 VPNs Virtual Router VPNs Is simple to implement Is scalable Is easy to provision new services Provides high security Is a securable network Supports many subscribers Requires MPLS/BGP Supports interoperability Provides end-to-end QoS Reduces CPE complexity Reduces CPE processing Chapter 9 IP Services MPLS was first deployed in the core of carrier networks to enhance the perfor- mance and capabilities of connectionless IP routing. Today, there is increased inter- est in MPLS Layer 2 VPN services. With MPLS Layer 2 VPN services, carriers transport protocols such as SNA, DECnet, or IPX and keep legacy TDM private lines as well as Frame Relay and ATM services. With Layer 2 VPNs, the provider forwards packets based on Layer 2 information or port information. It emulates Layer 2 WAN or LAN connectivity between customer sites. In this case, the cus- tomer is responsible for the Layer 3 routing. Layer 2 MPLS VPNs are identical to private network VPNs in that the customer attaches its customer premises router to the MPLS cloud via traditional Layer 2 circuits and builds a Layer 3 routing topology over the provisioned circuits. The management of the routing is handled by the customer in the same fashion as it would be with a traditional private VPN. In a Layer 2 VPN solution, there is no exchange of routing information between the provider edge and the customer edge. The IP/MPLS service provider core net- work transports customer Layer 2 frames from ingress provider edge to egress pro- vider edge. The VPN tunnels that transport this traffic between provider edges are called pseudo-wires, as they emulate the behavior of a connection or wire over a con- nectionless infrastructure. The provider edges implement Layer 2 VFIs that forward the customer traffic based on La