s in TS31 (or any other time slot) are used. If an MCB (master control bit) is used, this indicates whether or not the clock timing is based on the master, with '0' indicating that it is based on the timing sent by the master and '1' indicating that the timing is not based on the master. If synchronisation is based on the master-slave technique, then MCB '1' also indicates that there is some fault with the flow of the timing signal and the equipment is not receiving timing from the master. The LCB (loop control bit) would indicate '0' when there is the possibility of a timing loop, which means that if there is a loop topology in the network, the LCB would be '0' indication that the timing loop is not there (based on the principle of synchronisation planning explained above). As every element should have more than one clock source, SO the LCB indicates from where the equipment should take its timing signal. So: MCB: 0 - signal is based on the master clock MCB: 1 - signal is based on some other clock (e.g. internal) LCB: 0 - synchronise slave from master, no possibility of timing loop LCB: 1 - do not synchronise slave from master (e.g. there may be possibility of a timing loop). 3.4.5 Transmission Network Management Planning Network management systems (NMS) can be of many types. They may be able to manage the whole network or may be specifically for management of the transmission element. Generic applications of network management systems include network element (and con- figuration) management, security management, alarm management, performance and fault management. Network element (NE) and configuration management functions may include controlling the NE, collecting and providing the data to the NEs. This function also makes integration of the NE to the network possible. The alarm management function enables the user to collect the alarms from the NEs. These alarms indicate the status of these NEs. The fault management function detects failures and schedules the correction of these faults, apart from testing and 