North-south traffic refers to the traffic flowing between the network perimeter (such as a data center or a cloud) and external entities, such as end-users accessing the network from the internet or other remote locations. This type of traffic usually passes through firewalls, intrusion detection systems, and other security measures that are typically placed at the network edge to protect against external threats.
On the other hand, east-west traffic refers to the traffic flowing between entities within the network perimeter, such as between servers, switches, and storage devices. This type of traffic usually stays within the internal network and is generally considered to be more secure than north-south traffic since it doesn’t have to pass through as many security controls.
In general, north-south traffic tends to have a lower volume but a higher variety of protocols and applications, while east-west traffic tends to have a higher volume but a more limited set of protocols and applications. Understanding the patterns and volume of both north-south and east-west traffic is important for designing and optimizing network architecture, security, and performance.