CISCO IoT Reference Model

A popular model for IoT is the CISCO IoT Reference Model which consists of 7 levels:

Level 1: Physical Devices and Controllers (Edge; Things)
  •  This level is also called the "edge level".
  •   It contains the "things", such as sensors, devices and machines, virtual objects.

Level 2: Connectivity
  •  This level consists of the communication and processing units.
  •  It carries out routing, switching, and the translation of protocols.  
  •  It facilitates communications between Level 1 devcices and with Level 1 devcices, as well as communication across networks.
  •  Security and self-learning network analytics are also provided at this level.

Level 3: Edge (Fog) Computing
  •   This level receives the data packets and outputs data understandable to higher levels.
  •   It combines network and data level analytics.
  •   It performs data element analysis and transformation, data filtering, cleanup, aggregation, and packet content inspection. 
  •   It can also generate events.
Level 4: Data Accumulation (Storage)
  •  This level converts data-in-motion to data-at-rest.  
  •  Data format is converted from network packets to database relational tables.  
  •  It transforms event-based computing to query based computing.  
  •  Data is also reduced through filtering and selective storage.

Level 5: Data Abstraction (Aggregation and Access)
  •  This level creates schemas and views of data in the manner that applications want.
  •  It combines data from multiple sources.
  •  It simplifies, filters, selects, projects and reformats data to serve client applications. 
  •  It reconciles the differences in data shape, format, semantics, access protocol and security.

Level 6: Application (Reporting, Analytics, Control)
  •  This level controls the applications and performs business intelligence and analytics.

Level 7: Collaboration and Processes
  •  This level involves the people and business processes.

Levels 1 to 3 are also called the "edge-side layer".

Levels 4 to 6 are also called the "server/cloud-side layer".

Level 7 is also called the "user-side layer".