What is token bus network?
A token bus network is very similar to a token ring network, except that the ends of the network do not meet to form the ring. Instead, the network is still terminated at both ends.
A token is still required before a node can use the network. As in a token ring, the address of the destination must be included along with the data that must be sent. Although implemented on the token bus, it implements a virtual ring on the coaxial cable.
Although both topologies use tokens, the similarities end there because the token bus uses a different topology and the token passing protocol is different. In a token ring network, the token and data are forwarded to the next physical node along the line, but in a token bus network it does not matter where the nodes are physically located because token passing is via a numerical sequence of node addresses. The token or the data are forwarded to the next sequential node address, regardless of whether the physical location of this node is at the end of the bus network. This is the virtual ring. It won't change the physical layout of the network.
Token bus networks are defined by the IEEE 802.4 protocol.
Token bus networks are basically similar to Token Ring networks, but they differ in practice. For one, it uses a different topology, a bus topology, and the method of passing tokens is different. Compared to a token ring, which forwards tokens and data to the next physical node in the ring, token bus networks use a virtual ring in which all nodes have different sequence addresses that the token and data must pass through. The physical location of the nodes is irrelevant in the token bus topology. It is the sequence address of the nodes that matter where the token would go next until it reaches its destination.
Token bus networks are mainly used for industrial applications such as manufacturing. The IEEE 802.4 working group has disbanded, which means that the standard is no longer updated and is not widely used.