The rapid acceptance and accelerated growth of the Internet is quickly transforming the mix of traffic crossing public networks. To compete effectively in a data-driven economy, service providers need an optical transport infrastructure optimized for packets combined with the scalability and the flexibility to support unimagined IP-based applications.Cisco Systems, Inc. has developed the Quad OC-12/STM-4 packet-over-SONET/SDH line card. This new high-density interface card offers industry leading switching performance and class-of-service (CoS) features for delivering advanced end-to-end networking features. The high performance switching engine integrates WRED and the innovative ASIC-based queue scheduling algorithm Modified Deficit Round Robin (MDRR) in the core of the network. These allow service providers to offer differentiated services with deterministic traffic behavior in the core of the network. This unique combination of features provides a versatile solution allowing a service provider to deploy a single interface in either a core application or a high-capacity aggregation application. This level of flexibility helps improve protection of investment, which is ideal given the dynamic nature of an Internet-driven economy.