My guess would be that you have a spanning tree issue which is causing topology changes in the network, hence the MAC address moves and the short aging timer i.e., the same value as the forward delay, being seen for VLAN 600.
If you run the show spanning-tree vlan 600 detail command the first few lines of the output will indicate the number of topology changes that have occurred, when the last one was and the interface it was received from.
The switch you captured the above commands on is the root bridge for the spanning tree, and the switch connected to interface gi3/11 is the device generating the Topology Change Notification (TCN) and then sending to the root bridge.
Can you login to the downstream switch that is connected to interface gi3/11? If so then run similar commands on that switch and see which port is causing the topology changes. It may be that you have a port that is continually changing state.
If it's an access switch, then changing the port type to an edge port i.e., enabling portfast, will stop the TCN being generated.
We are pleased to announce availability of Beta software for 16.6.3.
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