networksunder

networksunder is a term used in information technology to refer to the underlying network infrastructure that supports higher-level network services. It describes the substrate on which communication takes place, encompassing the physical media, routing and switching fabrics, and the control and management planes that govern data transfer. This term is not uniformly standardized and its precise meaning can vary by context, but it is generally applied to describe what lies beneath overlays, virtual networks, and application-layer networking.

The components of networksunder typically include physical connectivity (fiber, copper, wireless links), transport networks, data-center and campus fabrics, and the software-driven control mechanisms that operate them. In many environments, networksunder also encompasses the mechanisms for provisioning, policy enforcement, performance tuning, and fault management that ensure reliable end-to-end communication. Software-defined networking (SDN) and network virtualization often treat the underlay as a distinct layer that must meet latency, bandwidth, and resilience requirements, while overlays provide flexible, tenant-specific networking on top of it.

In practice, distinguishing networksunder from overlay networks helps network engineers optimize visibility, troubleshooting, and security. It is especially important in large-scale data centers, enterprise WANs, cloud deployments, and carrier networks, where a well-managed underlay is critical to overall performance and reliability. The term serves as a conceptual reminder of the foundational role that substrate networks play in modern connectivity.