Problem Description：
No matter how many alarms on the USN, they cannot be seen on the eOMC side.
Problem Analysis：
By viewing the exported historical alarms, the USN network element disconnection time is 2019-01-16 13:28, and its reconnection time is 2019-01-16 13:28. After the communication, the alarms that are not seen on the eOMC are all S1ap Link Down alarms.
Check the log and find that the link node connection of the USN network element fails in the connection process of 2019-01-16 13:28. (The reason for the connection failure is that the link node is starting up).
Check all the alarms that are not synchronized. The alarms are reported by the link node. The eCore expert confirms that if the link node is not connected successfully, the corresponding alarm will not be reported. Therefore, the alarm reported by the link node cannot be seen on the eOMC.
The USN is a multi-node network element. The nodes start in the sequential order, and the master node starts successfully firstly, the other nodes (non-master nodes) are started in a multi-threaded manner. At this time, the USN does not prevent eOMC from issuing commands to connect.
When the eOMC connects to the USN, the nodes that successfully start will be connected, and the node that is starting will fail to connect. If the nodes on the connection contain the master node, the eOMC will display the connection success status on the TOPO view, but the link node (non-master node) that is actually starting is not successfully connected, and will not actively connect to the link node. The alarms reported by the link node on the USN cannot be synchronized to the eOMC.
The USN should wait for all the nodes to start successfully so that the eOMC can connect to the network. Instead of the master node is successfully started, the eOMC can issue commands to connect. However, the startup connection mechanism of the USN network element is difficult to modify. Therefore, the eOMC needs to adapt to the startup connection mechanism of the USN.
Root Cause：
The reconnection mechanism between the OMC and eCore needs to be optimized.
Solution Description：
Circumvention measures: Reconnect the USN network element.
Solution:
Modify the code, adapt the network element's start-up connection mechanism, and wait for all nodes of the USN network element to start successfully before connecting to the network element.
It is planned to be solved in the 5.1 X5+ version released at the end of April 2019.
