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Context:
- All CPUs are concerned (BMEx58x0x0x)
- CPU configured as NTP client (both IPs: IPA and IP Main)
- IP A and IP Main are not on the same subnetwork (IP A = 192.168.11.3/24 and IP Main = 192.168.10.1/24)
- but a router is only set on one of the both subnetwork (i.e. 192.168.10.254/24 )

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Behaviour:
Randomly, on boot CPU phase, communication is starting with NTP server using IP A, NTP server is not reachable. => because router is only set for 192.168.10.x addresses.

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Nota:
This boot phase and random behaviour are documented in "Modicon M580, Hardware Reference Guide" (ref. EIO0000001578) into chapter "Installing Modules in an M580 Rack"/"Services and Addresses"



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Troubleshooting:
To avoid NTP packet filtering from the router, we recommand to configure the router subnetwork mask to 255.255.0.0 (16) instead of 255.255.255.0 (24)

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Appendix 1: Example of IP Main and IP A


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Appendix 2: example of NTP server

Released for: Schneider Electric Hong Kong