The OC-3c/STM-1c ATM line card expands the connectivity options for the Cisco 12000 series Internet routers so that service providers can attach the Cisco 12000 series router directly to their existing ATM infrastructure. This allows Internet service providers (ISPs) to offer wire-speed Internet access via ATM virtual circuits (VCs). The new line card performs the segmentation and reassembly (SAR) of IP packets in accordance with RFC 1483, Multiprotocol Encapsulation over ATM Adaptation Layer 5 (AAL5).The Cisco 12000 series ATM line cards enable the integration of legacy ATM networks with next-generation IP backbones in a multitude of ways. The ATM line cards for the Cisco 12000 series will enable service providers to build tomorrow's Internet.