Our software technology stack is mainly Java with micro-service frameworks(e.g. Spring Boot, Consul). And we're moving from VM to Kubernetes. Considering cases of putting consumer or/and registry conponents outside of the Kubernetes cluster, we have to make our network plane allows workload accessing Pod IP, Service IP from outside the Kubernetes cluster.

Our on-premise environment consists of several VLAN(layer 2 network), each VLAN is created by VCenter. Physically, every VLAN is based on several bare metal machines on the same floor, the bare metal machines are connected by ethernet switches. And we have several floors of bare metal machines, they're connected by ToR(Top of Rack) routers(layer 3 network).

I'm going to talk about my comprehension about Calico.