East-West Traffic

East-west traffic refers to network traffic that occurs within an organization's internal network, as opposed to traffic that enters or exits the network (referred to as "north-south" traffic).

East-west traffic typically refers to communication between servers, workstations, or other devices within a data center or between different data centers within an organization. This type of traffic often involves the exchange of large amounts of data as services or applications may rely on data from other components, services, or applications to function correctly. Examples include database replication, file transfers, and inter-process communication.

Key characteristics include:

1. Server-to-Server Communication: As named, this primarily involves communication between different servers, services, or applications hosted within the same data center or cloud infrastructure. This traffic can encompass a wide range of data exchanges, including database queries, application requests, inter-service communication in microservices architectures, and more.

2. Within the Data Center: It stays within the boundaries of the data center or cloud region, which means it doesn't traverse perimeter security devices like firewalls or gateways. As a result, east-west traffic typically occurs within a trusted network segment, and security measures must be implemented within the data center itself to protect against potential threats and unauthorized access.

3. Horizontal Scalability: In modern data center architectures, applications and services are often designed to scale horizontally by adding more servers or instances as needed. This leads to an increase in east-west traffic as these instances need to communicate and coordinate with each other.

4. Complexity: Managing east-west traffic can be complex due to the dynamic nature of modern data centers and cloud environments. Automation, load balancing, and security policies are often necessary to ensure that traffic flows efficiently and securely.

In a modern, cloud-based infrastructure, east-west traffic is critical as more applications are deployed across multiple data centers and cloud platforms such as Amazon Web Services and Google Cloud. Proper management of east-west traffic is crucial for ensuring the performance and security of these applications. To achieve this, organizations may use network segmentation or micro-segmentation techniques to restrict and control the flow of east-west traffic within their networks.

Note that network segmentation does not fully fix the Perimeter Problem. From a security perspective, establishing east-west mTLS is strongly suggested to limit lateral movement and allow each individual resource to apply access control.