Control Plane Ingress IP management with MetalLB L2 does not work (by design) with multiple L2 segments for control plane network

[TeddyAndrieux]

Component:

'metallb', 'network'

What happened:

Currently, MetalLB L2 does not support nodes in different L2 segments see metallb/metallb#511

But even if MetalLB does current design in MetalK8s for control plane ingress with MetalLB cannot work as-is if we have control plane node that sits in different L2 segments, since we define a single VIP that, obviously, cannot be part of the various L2 segments we define for the control plane.

What was expected:

To be discussed/design

Several possibilities

• Forbid MetalLB L2 management when we have multiple L2 segments and let the user manage the (V)IP
• Forbid MetalLB L2 management when we have multiple L2 segments and only support MetalLB BGP in this case
• Allow defining multi VIP for control plane ingress, so that if you have multiple L2 segments you can define a VIP per L2 segments (if you want to) (NOTE: to do this approach we first need the MetaLB issue mentioned above to be fixed otherwise it will not work)

Resolution proposal (optional):