Load balancer options in GKE on Bare Metal
GKE on Bare Metal supports two load balancer options: bundled and manual.
Bundled load balancer mode
If you choose bundled load balancing, the load balancer is provided for you. An external load balancer is not needed.
There are two types of bundled load balancing:
Layer 2: All load balancer nodes and VIPs must be in the same Layer 2 subnet. The gateway of the load balancer subnet must listen to gratuitous ARP messages and forward ARP packets to the load balancer nodes. See Bundled load balancing with MetalLB.
BGP: This load-balancing mode supports the advertisement of ServiceType LoadBalancer virtual IP addresses (VIPs) through external Border Gateway Protocol (eBGP) for your clusters. Your cluster network is an autonomous system, which interconnects with another autonomous system, an external network, through peering. See Bundled load balancing with BGP.
The following diagram shows an example network topology where bundled MetalLB load balancers are located on the control plane nodes.
Manual load balancer mode
If you choose manual load balancing, GKE on Bare Metal does not deploy load balancers. This allows more flexibility than bundled load balancing and there are no L2 network requirements.
You must configure your control plane nodes' VIPs on an external load balancer before installing the cluster. After installation, you must pick a load balancing solution for Kubernetes Services and Ingresses.
The following diagram shows an example network topology of a cluster using manual load balancing mode with an external load balancer.
