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The NIM (network interface manager) microservice is already testing the connectivity towards the controller, and is also detecting when complete local connectivity is lost (the cable being unplugged and/or the DHCP lease expiring). The result pf that That checking and testing results in updates to the DeviceNetworkStatus `DeviceNetworkStatus` object. That testing mechanism will be extended to test all of the management ports, and report the lastSucceeded/lastFailed timestamps in the DeviceNetworkStatus `DeviceNetworkStatus` per each port.
The zedrouter microservice (which implements the network instances) will observe these changes and use it them to update the network instance's use of the port, and the associated NAT rules (MASQUERADE and port map rules) to be associated with the currently used management port. Also, the PBR rules for the source IP address of the network instance (shown in ip rule show) will be updated to refer to the table associated with the currently used management port.
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