Cisco pays special attention to its network accessories, which are the foundation stone of the whole network system. The company offers a variety of connectivity, expansion and upgrade options to accommodate the customer specific needs. Cisco's components are easily and inexpensively upgradeable as customer requirements change.Cisco Mechanical Interface Cards provide the physical connection points for the DS-1 and DS-3 interfaces on the XTC cards, the redundant power inputs, the alarm inputs and outputs, and the BITS timing inputs and outputs.