The TCC-I Timing Communication and Control Card performs system initialization, provisioning, alarm reporting, maintenance, diagnostics, IP address detection/resolution, SDH SOH Data Communications Channel (DCC) termination, and system fault detection for the ONS 15454 SDH. The TCC-I also ensures that the system maintains Stratum 3 E (G.813) timing requirements.The TCC-I supports multichannel, high-level data link control (HDLC) processing for the DCC. Up to 48 DCCs can be routed over the TCC-I and up to ten DCCs can be terminated at the TCC-I (subject to available optical digital communication channels). The TCC-I selects and processes ten DCCs to facilitate remote system management interfaces.The TCC-I also originates and terminates a cell bus carried over the module. The cell bus supports links between any two cards in the system, which is essential for peer-to-peer communication. Peer-to-peer communication accelerates protection switching for redundant cards.The node database, IP address, and system software are stored in TCC-I non-volatile memory, which allows quick recovery in the event of a power or card failure.The TCC-I performs all system-timing functions for each ONS 15454 SDH. The TCC-I monitors the recovered clocks from each traffic card and two BITS ports for frequency accuracy. The TCC-I selects a recovered clock, a BITS or an internal Stratum 3 E reference as the system-timing reference. You can provision any of the clock inputs as primary or secondary timing sources. A slow-reference tracking loop allows the TCC-I to synchronize with the recovered clock, which provides holdover if the reference is lost.