The Sync interface between Dual MHO's is used for configuration sync operations only, so that if a configuration change is made on one of them it will also be made on the other. That is it, there is no state table sync or anything else going on that will immediately impact the operation of the MHOs if the Sync interface goes down. So if the Sync interface goes down both MHO's will continue to pass traffic normally, although if a config change is made on one MHO and not propagated to the other in this state it could definitely cause traffic handling issues.
Yes you can have redundant Sync interfaces, you'd just need to change the type of the second port from whatever it is to type "Sync". Depending on the Orchestrator model there may be restrictions about what physical ports can be reassigned to be for Sync. There’s no need to manually create a Bond interface as it will be created automatically by the Orchestrator when the second Sync interface is defined. The bond link aggregation will operate in XOR mode.
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