The rapid growth of Internet-enabled user applications has led to an increase in the bandwidth provisioned through service provider networks. To accommodate this growth, service providers are consolidating existing network architectures that deliver traditional Layer 2 WAN services, such as Frame Relay and ATM, with architectures that deliver Layer 3 WAN services, such as high-speed Internet access and Layer 3 VPNs. This network consolidation enables service providers to optimize their capital investments so that all such expenditures simultaneously benefit all network services.Achieving network consolidation is particularly challenging at network aggregation points. The devices at these points must be able to deliver multiple Layer 2 and Layer 3 services, while providing efficient transfer of network traffic from customer access nodes to the core network and back. These aggregation devices must simultaneously provide scalable bandwidth and interface density between the access and core networks; support numerous network protocols, as well as quality-of-service (QoS), security, and accounting features; and be compatible with the existing SONET infrastructure.