I have a colleague who is migrating a customer from one cluster running legacy R77 version to a new cluster running R80.20. The customer is very sensitive to down time and when they tried migration attempt 1, it appears that some network devices took longer to clear the ARP cache and therefore they had minutes of downtime for certain services.
Normally we would ask the customer to liaise with the 3rd party who manages the network to co-ordinate with us and clear the ARP cache during the maintenance window post migration but for reasons I won't go into, this is not an option.
This got me to thinking about VMAC mode. We use this when clustered gateways which have a lot of interfaces and the volume of G-ARPs after a failover means that the switches ignore them. Would it be possible to manually configure the MAC address used in the VMAC mode. This way, we can configure this on the new cluster and make live after halting the old cluster. This way the network devices don't have to re-learn anything other than associated switch ports for the MACs.
Look forward to feedback and any other alternative suggestions.