Problem pinging redundant AC800M controllers via NE870 RNRP Routers

We are setting up a system with NE870 RNRP Routers and cannot ping the redundant controllers having addresses in area 172.16(17).82.xx from computers in the Client/Server network.

We can ping the 172.16(17).80.xx and 172.16(17).82.xx from the RNRP-routers using the web interface.

The system is set up with client/server addresses in area 172.16.8.0 /22, and the ControlNet in 172.16.80.0/22.

We have tried to fault trace using below input from another post:
Based on the below questions, we cannot find any obvious errors:

1. Verify the backup address by pulling the controller log (default is backup interface disabled).
2. Verify that primary controller does not report "Primary: no communication with backup". Such warning will be raised if primary cannot "ping" secondary.
3. Verify that NE870 can ping backup controller (use web interface or SSH/CLI)
4. Verify that ICMP is not blocked in the firewall
5. Backup address, using default rule (0.0.+2.0) require a /22 network mask.

Attached a few screenshots showing our configuration:

1:RNRP Interfaces:

2: Firewall configuration, RNRP Packet filter rules:

3: TCPDUMP printout

Any tip or suggestion how to solve this is appreciated.

Thanks in advance

BR
Henrik Sandvin

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Asked 3 months ago

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IIRC: A controller acting as backup does not actively run RNRP. As a result, its routing table does not have any path allowing it to send or reply any telegram outside of its own subnet.

The primary is constantly exchanging Ethernet telegrams with the backup and a warning will be generated if the backup does not reply.

At switchover, the backup will instantaneously take over the primary’s Ethernet MAC address and resume regular RNRP operation, along with execution of the control applications.

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