Cisco offers a variety of connectivity, expansion and upgrade modules and cards to accommodate the customer specific needs. Cisco's components are easily and inexpensively upgradeable as customer requirements change.The one-port OC-12/STM-4 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).