Industrial Internet Connectivity Framework | Page 15

Connectivity Framework

2: Connectivity Framework

The lowest layer is the physical layer, which refers to the exchange of physical signals( electric, optical, or other) on the physical media( wired or wireless) connecting the participants. Above it is the link layer, which refers to the exchange of frames using signaling protocols on the shared physical link between adjacent participants. Above it is the network layer, which refers to the exchange of packets( bounded length), possibly routing them over multiple links to communicate between non-adjacent( remote) participants. Above it is the transport layer, which refers to the exchange of messages( variable length) between participant applications. Above it is the framework layer, which refers to the exchange of structured data( state, events, streams) with configurable quality-of-service between participant applications. Above it, but outside the scope of connectivity, is the distributed data interoperability and management layer crosscutting function that relies on the data sharing mechanism provided by the connectivity framework layer.

The Internet Protocol( IP)( Wikipedia) 1 is the prevailing network layer connectivity standard that has given birth to the internet and now IIoT. The IP network layer has enabled independent innovation, both below and above the network layer. The bottom three layers, common to the OSI model and the Internet model, have been in use longer and are generally understood; although evolution of IP and non-IP connections and the multitude of wireless-access technologies coming to market create new choices for the IIoT community.

Figure 2-2: The focus of this document is on connectivity layers above the network layer, namely the connectivity transport and the connectivity framework layers.

1

See [ IETF-RFC1122 ], for overview [ WKPD-IPS ] IIC: PUB: G5: V1.0: PB: 20170228- 15-