 cost reductions on a single edge device. The multiservice edge is an emerging market segment of edge devices optimized for converging Layer 2/Layer 3 services over IP/MPLS. A multiservice edge device must be designed from inception for full multi- service convergence. This includes the requirement to deliver high reliability, pro- vide a modular and flexible architecture, enable multiservice optimized traffic management, and support intelligent integration into existing infrastructures. The multiservice edge involves two key components: routing switches, which perform full routing and switching and offer scalability and full IP functionality distributed to the line cards, and service routers, which perform full Internet routing with the mechanisms to enforce VPNs based on SLAs. Service edge router requirements include combining routed and switched data services, particularly because new services do not necessarily replace old services. Another requirement is an interface to TDM and packet access networks (see Fig- ure 10.10). Again, access networks are not readily replaced. The service edge router must adapt multiple services for delivery across a common packet core, with the core being transparent to the customer, and it is a key point for mapping ser- vices into network QoS. Finally, it must manage a large number of customer inter- faces, both physical and logical. Service providers also want to allow their customers to determine the rate at which they move from Frame Relay and ATM to IP/MPLS. Ideally, service providers would like to allow their customers to use any access method they want and oper- ate as a single VPN. This means enterprise customers could keep low-speed Frame Relay at some sites while upgrading other sites to Ethernet services. For the service providers, this means the potential for better service margins, greater customer retention, and the potential to increase the share of enterprise spending by bring- ing additional locations into the VPN service. The multiservice edge must support missi