Platform & DevOps·Traffic into and inside the cluster
one internal service calling another, which is most of your packets and historically none of your authentication.
East-west traffic
Also calledeast/west, service-to-service traffic, internal traffic
Traffic between services inside the boundary. In a microservice estate it dwarfs the north-south volume, and it was traditionally unauthenticated and unencrypted on the assumption that the network was trusted. Making it verified — workload identity, mutual TLS, per-call policy — is precisely what a service mesh and a zero-trust posture are for, and it is why anything compromised inside the perimeter used to be able to reach everything.