I learn from envoy’s offical doc，envoy support Locality Load Balancing；and in istio offical doc，I see istio use Region/ Zone/ Sub-zone to realize Locality Load Balancing.
I Istio pilot source, I see code use topology.kubernetes.io/region to label region info
Can anyone tell me,how these componet(pilot/istio/envoy) togther to realize Locality Load Balancing