{{Short description|Implementation of Token Ring using a virtual ring on a coaxial cable}} {{Use British English|date=January 2021}} [[File:Token bus.svg|thumb|Token passing in a token bus network]] In computer networking, a '''token bus network''' is a network implementing a token-passing protocol over a virtual ring on a coaxial cable.<ref>{{cite web |url=http://www.linktionary.com/t/token_bus.html |title=Token Bus Network |access-date=2012-03-21}}</ref>
==Network== A token is passed around the network nodes and only the node possessing the token may transmit. If a node doesn't have anything to send, the token is passed on to the next node on the virtual ring. Each node must know the address of its neighbour in the ring, so a special protocol is needed to notify the other nodes of connections to, and disconnections from, the ring.<ref>{{cite web |url=http://www.technologyuk.net/telecommunications/networks/token_bus.shtml |title=Token Bus (IEEE 802.4) |access-date=2012-03-21 |archive-date=2012-04-12 |archive-url=https://web.archive.org/web/20120412203225/http://www.technologyuk.net/telecommunications/networks/token_bus.shtml |url-status=dead }}</ref>
Ethernet's access protocol could not absolutely guarantee a maximum time any station would have to wait to access the network, so was thought{{who|date=August 2018}} to be unsuitable for manufacturing automation applications. The Token bus protocol was created to combine the benefits of a physical bus network with the deterministic access protocol of a Token Ring network.<ref>{{cite web |url=http://www.inetdaemon.com/tutorials/networking/lan/token/ |title=Token Bus and Token Ring |access-date=2012-03-21}}</ref>{{dubious|Development order|date=January 2021}}
==IEEE 802.4== '''Token Bus''' was standardized by '''IEEE standard 802.4'''. It was mainly used for industrial applications. Token Bus was used by General Motors for their Manufacturing Automation Protocol (MAP) standardization effort.<ref>{{cite journal |title=The IEEE token bus-A performance bound on GM MAP |volume=35 |pages=13–17 |journal= IEEE Transactions on Industrial Electronics|date=February 1988 |author1=Weaver, A.C. |author2=Summers, C.F. |doi=10.1109/41.3057}}</ref> This differs from Token Ring networks in that the endpoints of the bus do not meet to form a physical ring.
In order to guarantee the packet delay and transmission in the Token Bus protocol, a modified Token Bus was proposed in manufacturing automation systems and flexible manufacturing system (FMS).<ref>{{cite web|url=https://www.proquest.com/docview/303683230 |title=An Industrial FMS Communication Protocol |access-date=October 8, 2023 |id={{ProQuest|303683230}} }}</ref> To optimize deterministic access required by real-time IoT communication in a distributed manufacturing plant or IIoT, token bus method can also be implemented according to IEEE 802.15.4.<ref>{{cite web|url=https://www.iis.fraunhofer.de/content/dam/iis/de/doc/lv/nsa/Flyer/IoT-Bus_for_Automation.pdf |date=2023|title=IoT-Bus for automation; Albert Heuberger; Retrieved on 8 October 2023}}</ref>
A means for carrying Internet Protocol over IEEE 802 networks, including token bus networks, was developed.<ref>RFC 1042</ref>
The IEEE 802.4 Working Group has disbanded and the standard has been withdrawn by the IEEE.<ref>{{cite web |url=http://www.ieee802.org/dots.shtml |title=IEEE 802 Working Group & Executive Committee Study Group Home Pages |publisher=IEEE 802 LAN/MAN Standards Committee |access-date=2012-03-21}}</ref>
== See also == * ARCNET * Network topology
==References== {{reflist}}
{{Channel access methods}} {{IEEE standards}}
{{Authority control}} {{DEFAULTSORT:Token Bus Network}} Category:Local area networks Category:IEEE 802 Category:Link protocols