Platform & DevOps·Traffic into and inside the cluster
the traffic crossing the boundary between the outside world and your platform, which is the part that has a certificate and a WAF.
North-south traffic
Also callednorth/south, edge traffic, client traffic
Traffic in and out of the system as a whole — users, partners, the public internet. It is the smaller volume and the more scrutinised: it is where authentication, TLS termination, rate limiting and DDoS protection are applied, and where an external load balancer sits. Drawing the distinction matters because controls designed for this direction are routinely assumed to protect the other one, and they do not.