4 Port OC3/STS3c/STM1c ATM Line Card, single mode.The Cisco 10000 Series Four-Port OC-3c/STM-1c Asynchronous Transfer Mode (ATM) line card provides both the performance and the density to scale networks efficiently and reliably. It features a high-performance segmentation and reassembly (SAR), adapted for various applications including advanced traffic management, cell scheduling, and integrated buffer management. By mapping IP class of service (CoS) to ATM quality of service (QoS) on the Cisco 4-Port OC3c/STM1c ATM Line Card, the flow of mission-critical data can be effectively managed across heterogeneous IP and ATM networks.