Southbound protocols connect to a network's physical devices; what is the name of the database or registry of the services provided by the southbound APIs?

Southbound protocols connect to a network's physical devices; what is the name of the database or registry of the services provided by the southbound APIs?

• A. Service Abstraction Layer
• B. Service Access Layer
• C. Storage Abstraction Layer
• D. System Abstraction Layer

Answer: (A)

The main idea here is the layer that inventories and standardizes what the devices behind southbound protocols can do. The Service Abstraction Layer serves as a registry of the services exposed by the southbound APIs, translating diverse device capabilities into a uniform set of services that higher layers can discover and use. It abstracts hardware specifics so controllers see consistent service definitions—like flow handling, metering, and port configuration—regardless of the underlying device. That’s why it’s the best fit: it explicitly represents a catalog of services offered through the southbound interface, bridging the gap between diverse hardware and the higher-level control plane. The other options don’t capture this registry function: a Service Access Layer implies merely accessing services, not cataloging them; a Storage Abstraction Layer focuses on storage devices; a System Abstraction Layer is too broad and not specifically about listing southbound-exposed services.

The main idea here is the layer that inventories and standardizes what the devices behind southbound protocols can do. The Service Abstraction Layer serves as a registry of the services exposed by the southbound APIs, translating diverse device capabilities into a uniform set of services that higher layers can discover and use. It abstracts hardware specifics so controllers see consistent service definitions—like flow handling, metering, and port configuration—regardless of the underlying device.

That’s why it’s the best fit: it explicitly represents a catalog of services offered through the southbound interface, bridging the gap between diverse hardware and the higher-level control plane. The other options don’t capture this registry function: a Service Access Layer implies merely accessing services, not cataloging them; a Storage Abstraction Layer focuses on storage devices; a System Abstraction Layer is too broad and not specifically about listing southbound-exposed services.