The controller cards incorporate a highly stable internal timing reference to provide system timing based on input received from an external BITS source. Synchronous status messaging helps the system select the optimal timing sources, and a holdover mode maintains timing accuracy, when pre-provisioned synchronization references are not available. The cards have two built-in interface ports for accessing the system: an RJ-45 connector and an RS-232. The RJ-45 port provides 10Base-T Ethernet connectivity to the system, providing local and remote access to the craft-management system, Cisco Transport Controller, through a common web interface. You can also use this port for interconnection to customer operations support systems (OSSs) and network management systems (NMSs), providing integration to external element management systems (EMSs), NMSs, and OSSs.