NEMA NTCIP 2104:2003

This standard is applicable to transportation devices and management systems that must operate in Intelligent Transportation Systems. It specifies a set of protocols and standards applicable to the data link and physical layers of the OSI Basic Reference Model. It specifies a combination of ISO/IEC Standards that collectively provide for connectionless and connection-oriented data link services on a common, shared media. Access to the media is through a process referred to as carrier sense multiple access with collision avoidance detection (CSMA/CD). It also defines the interface to and specification of the shared media. Networks based upon this technique are often, but mistakenly, referred to as Ethernet-based Networks. This standard deals with IEEE 802 Networks that have additional functionality. Although similar to Ethernet based Networks, IEEE 802 Networks are distinguished by inclusion of Logical Link Control (LLC) and Media Access Control (MAC) layers.