Anthos on bare metal only requires L3 connectivity for worker nodes, but requires L2 connectivity among control plane nodes to announce VIPs. The load balancer can be run on a separate node pool or on the control plane node pool. The same L2 network requirements apply if the load balancer is run on the control plane node pool
Control plane traffic all goes through the control plane VIP, so load balancer setup is required during cluster startup.
The requirements for load balancer machines are:
The following figure describes the logical configuration of an Anthos on bare metal environment with a non-HA control plane: