i appreciate all of your answers.
Another note on the example:
Firewall A will have a static route set beforehand for 10.10.10.0/24 via an existing linknet to Firewall B. The idea is to ensure, that after migration of vlan interface 10, services from Firewall A can still communicate with Firewall B, once the direct-connected interface, and therefore the d-c route, is deleted on Firewall A, and the static route will be the best route.
Regarding VLAN Interface Removal and VLAN Monitoring:
Thank you @Chris_Atkinson . I will go through our current configuration regarding sk92826- as i understand it, as long as CP cluster is in default configuration, the monitored VLAN interfaces for HA failover should be lowest (e.g. vlan1) and highest (e.g. vlan4094).
Regarding the steps to "disable" the Cluster VLAN Interface:
Is there no other way to get rid of the cluster interface supplying the exampled default gateway 10.10.10.1?
I am thinking of changing the prefix on the vlan 10 interface to some RFC specified non-routed prefix e.g. 169.254.1.1, so that i can keep the interface in smart console? This might be a more wild implementation, but might work.
The reason i am asking is, i will have to do the exampled vlan migration for roughly 50 vlan interfaces. Hence, i would like the steps on the production Firewall A as small as possible.
@the_rock : Is get interfaces without topology mandatory, after deleting the interfaces on the gateways? I typically don't use "get interfaces with/without topology" at all, hence the question.
The steps that i would go for, if no other steps are recommended, are these then:
1) On both gateways:
set interface eth1.10 state off
delete interface eth1 vlan 10
2) Smart Console
a) Delete vlan interface eth1.10
Gateways & Servers -> [Cluster Object] -> Network Management -> [eth1.10] -> Action -> Delete Interface