Fog Computing

@@ -34,12 +34,16 @@ The fog computing paradigm emerged from a specific problem: the proliferation of

An additional advantage is that processed data is most likely needed by the same devices that generated it: by processing locally rather than remotely, the latency between input and response is minimized without requiring any change in the cloud architecture. The idea itself is not new — in non-cloud scenarios, special-purpose hardware (signal-processing chips performing Fast Fourier Transforms) has long been used to reduce latency and CPU burden. Fog computing extends this principle to programmable, networked computing infrastructure.

### Defining properties of fog nodes

Fog computing is characterized by: proximity to end users; dense geographical distribution; context-awareness regarding computational and IoT resources; latency reduction and backbone bandwidth savings; and redundancy in case of failure. It also enables edge analytics and stream mining, which cloud-based analytics cannot perform at the required latency. Fog nodes can provide security for resource-constrained IoT devices by performing cryptographic computations that the devices themselves cannot execute.

## Architecture

A fog computing architecture consists of a control plane and a data plane. On the data plane, fog computing enables computing services to reside at the edge of the network as opposed to servers in a data center. Fog nodes — intermediate computing units between edge devices and the cloud — receive data from edge devices, process it locally, and forward only the relevant results or aggregated summaries to the cloud.

### NIST definition and the boundary with edge computing

The NIST Special Publication 500-325 (March 2018) formally defines fog computing as "a horizontal, physical or virtual resource paradigm that resides between smart end-devices and traditional cloud computing or data center" and states that this paradigm "supports vertically-isolated, latency-sensitive applications by providing ubiquitous, scalable, layered, federated, distributed computing, storage, and network connectivity."

NIST further distinguishes fog computing from edge computing: in the theoretical model, fog computing nodes are physically and functionally operative between edge nodes and centralized cloud. "Fog computing is most distinguished by distance from the edge." For smaller deployments, fog and edge computing are often used interchangeably; for large-scale smart city deployments, fog computing is a distinct intermediate layer.