The Cisco TNC, TNCE, TSC, and TSCE cards incorporate a highly stable Layer 3 internal timing reference to provide system timing based on input received from an external BITS source or from an incoming SONET or SDH optical signal. Synchronous status messaging helps the system select the best timing sources, and a holdover mode maintains timing accuracy when preprovisioned synchronization references are not available.Nonvolatile database storage for communication, provisioning, and system control is provided, allowing full database recovery and survivability with complete system power loss. In addition, short-term clock recovery is also supported, reducing the need to reset the calendar and ToD settings after a brownout or complete power outage. Unique to the Cisco ONS 15454 M6, ONS 15454 M2, CPT 600, and CPT 200 is a memory module built into the chassis. This external memory is synchronized with the memory of the TNC, TNCE, TSC, and TSCE, thereby providing a backup to the node IP address, software package, and circuit database. This synchronization provides faster time to recovery when the node is used in simplex mode during a control-card replacement. The Cisco TNC, TNCE, TSC, and TSCE cards have 2 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. The Cisco TNC, TNCE, TSC, and TSCE cards provide security enhancements, allowing you to configure the front panel and Cisco ONS 15454 M6, ONS 15454 M2, CPT 600, and CPT 200 chassis Ethernet interfaces as regenerators or provision them with individual IP and MAC addresses for segregated craft and DCC access. The RS-232 port provides a serial ASCII interface for local craft access using VT100 emulation so that you can enter Transaction Language 1 (TL1) commands directly over a Telnet session without the assistance of a browser. The front panels of the Cisco TNC, TNCE, TSC, and TSCE cards provide multicolored LEDs for a quick view of the status of the card activity, raised network alarms, shelf voltage input, LAN interface, and synchronization. Two front-panel buttons allow you to quiet an active external audible alarm (alarm-cutoff button) or test the working state of system LEDs. The Cisco TNC and TSC cards are supported beginning with the Cisco ONS 15454 MSTP Release 9.2.0 system software for both the Cisco ONS 15454 M6 and ONS 15454 M2 platforms. The Cisco TNCE and TSCE cards are supported beginning with the Cisco ONS 15454 MSTP Release 9.3.0 system software for both the Cisco ONS 15454 M6 and ONS 15454 M2 platforms, and the Cisco CPT 9.3.0 system software for both the Cisco CPT 600 and CPT 200 platforms. Deployed networks may consist of Cisco ONS 15454 nodes equipped with Cisco Timing, Communications, and Control Two (TCC2), TCC2P, or TCC3 processor cards.