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English
OSN3500 communication network generally adopts the master-slave synchronization method, i.e., the master clock with high accuracy and stability will transmit the clock signal to the slave clocks at all levels through the clock network, and the slave clocks at all levels will be synchronized with the clock signals from the upper level respectively to achieve the synchronization of the whole network. The slave clocks using the master-slave synchronization method usually have three operating modes. When all external timing references are lost, the slave clock enters the hold mode. The slave clock operates using the last frequency information stored before the loss of the timing reference signals as its timing reference. This mode can cope with external timing signal interruption failures of up to several days. There are two types of hold mode, permanent hold and 24-hour hold. The slave clock enters free oscillation mode when all external timing references are lost and memory of the timing references is also lost or not entered into hold mode at all.
Problem Description
The internal clock source ID is the same as the external clock source ID causing the network element clock to oscillate freely, and the fault is eliminated after unsetting the internal clock source ID.
Fault Category
- Clock synchronization
- S1_SYN_CHANGE
- LTI
Phenomenon Description
- The OSN 3500 clock configuration is described below:
- The clock source tracked by the line board is obtained from another device and has a higher priority than its internal clock source.
- The "High Priority Clock Source Recovery Method" is set to "Auto Recovery".
- The clock quality is set to "Auto Extract".
- Set the "Protection status" to "Enable extended SSM protocol".
- The board clock ID is not set.
- Set the internal clock source ID to "6".
- All clock source statuses are normal.
- The OptiX OSN 7500 clock configuration is described below:
- There are external clock sources.
- The external clock source and the internal clock source do not have clock IDs set.
- The synchronized clock source is provided by the clock source with the high priority level of the circuit board.
Products
OptiX OSN 3500
Cause Analysis
The OptiX OSN 3500 device and the OptiX OSN 7500 device are located in the same network, and the clock of the whole network is synchronized by the external clock source of the other device. This external clock source ID is "6", which conflicts with the OptiX OSN 3500 internal clock source ID. This causes when the OptiX OSN 3500 detects this external clock source signal, it checks its ID and mistakes it for the internal clock signal, and enters the free oscillation mode in order to avoid clock looping.
Operation Procedure
- In the main topology of the T2000, right-click on the network element icon of the OptiX OSN 3500 and select "Network Element Manager".
- In the function tree, select "Configuration > Clock > Clock Subnet Settings".
- Select the Clock Subnet tab.
- Set the Internal Clock Source ID.
- Click "Apply" to bring up the "Tip" dialog box, and then click "Close".
Description:
If the device does not have an external clock source, set the "Internal Clock Source ID" to "(None)"; if you need to set the ID of the internal clock source, make sure that it is not duplicated with the ID of other devices.
The OSN3500 SSN1SXCSA Crossover Clock Board Synchronous Timing Module uses Centralized Timing Distribution Mode as theclockmode. The Synchronized Timing Moduleselects aclocksourcefrom the referenceclocksourcesas the referenceclock.These referenceclocksources come from line boards, tributary boards, or external synchronizedclocksources. This generates a synchronized systemclocksource and an external synchronized source of 2 Mbit/s or 2 MHz.
