North-south traffic
In computer networking, north-south traffic is network traffic flowing into and out of a data center.
Traffic
Based on the most commonly deployed network topology of systems within a data center, north–south traffic typically indicates data flow that either enters or leaves the data center from/to a system physically residing outside the data center, such as user to server.Southbound traffic is data entering the data center. Data exiting the data center is northbound traffic, commonly routed through a firewall to Internet space.
The other direction of traffic flow is east-west traffic which typically indicates data flow within a data center.