What is the purpose of adding labels inside the global sources?

Adding labels inside the global sources serves the purpose of restricting communication to only those workloads that have the specified labels in the global source. This ensures that policy enforcement is precise and targeted, allowing operators to manage and control traffic more effectively between workloads in a secure manner.

By specifying labels, you can create granular policies that dictate which workloads can communicate based on defined criteria, effectively reducing the attack surface and enhancing security. This feature is essential for implementing a zero-trust security model, where only authorized entities are permitted to interact with each other.

In contrast, while enhancing performance metrics (as mentioned in one of the choices) might seem beneficial, it is not the primary function of labels in global sources. Similarly, allowing open communication protocols or standardizing access across environments does not align with the intended use of labels for specific communication restrictions. The focus is on security and control, making the use of labels in this manner fundamental to policy effectiveness in Illumio's architecture.