United States Patent
US Patent 4583088: Method and apparatus for controlling access to a…
US 4583088 · granted 1986-04-15
Abstract
A communication system comprises several transmission bus segments (A . . . G) to which data stations (ST) are attached. Node units (1 . . . 7) are provided for interconnecting the bus segments which are selectively activated in a predetermined sequence for authorizing message transmission by attached data stations according to any given access protocol. Thus, only small groups of stations contend for access, but all messages are distributed over the whole network. Activation of a bus segment is effected by an authorization message from an assigned node unit. A token message is used to pass the status enabling a node to activate its assigned bus segment, sequentially through all nodes of the network. Each node unit comprises a control unit (17) for sending and receiving token messages and segment activation messages, and further comprises unidirectional amplifier means and switches (11) for establishing a connection between two associated bus segments selectively in either direction.
| Patent Number | 4583088 |
|---|---|
| Title | Method and apparatus for controlling access to a communication network |
| Filed | 1983-05-24 |
| Granted | 1986-04-15 |
| Inventor(s) | Bux; Werner K., Rothauser; Ernst H. |
| Assignee | International Business Machines Corp. |
| CPC Classification | H04L 12/46 |
| Number of Claims | 54 |
Abstract
A communication system comprises several transmission bus segments (A . . . G) to which data stations (ST) are attached. Node units (1 . . . 7) are provided for interconnecting the bus segments which are selectively activated in a predetermined sequence for authorizing message transmission by attached data stations according to any given access protocol. Thus, only small groups of stations contend for access, but all messages are distributed over the whole network. Activation of a bus segment is effected by an authorization message from an assigned node unit. A token message is used to pass the status enabling a node to activate its assigned bus segment, sequentially through all nodes of the network. Each node unit comprises a control unit (17) for sending and receiving token messages and segment activation messages, and further comprises unidirectional amplifier means and switches (11) for establishing a connection between two associated bus segments selectively in either direction.
Claim 1
Method of controlling access to a communication network consisting of separate bidirectional transmission bus segments interconnected by node units, one or a plurality of datastations being connected to each bus segment, characterized by the following steps: setting one selected node unit (1. . . 7) into an active node status, sending an authorization message from the active node unit for authorizing only data stations (ST) attached to a predetermined one of the bus segments connected to said active node unit, which said predetermined one segment then becomes theactive bus segment, to contend for access, transferring by each node unit messages from authorized data stations of the active bus segment, received on the one connected bus segment, to other connected bus segments in a flow direction away from the active bus segment, and passing the active node status from the currently active node unit to a predetermined next node unit, and repeating the above steps until all node units and bus segments were activated in a predetermined sequence.
Claims
54 totalMethod of controlling access to a communication network consisting of separate bidirectional transmission bus segments interconnected by node units, one or a plurality of datastations being connected to each bus segment, characterized by the following steps: setting one selected node unit (1. . . 7) into an active node status, sending an authorization message from the active node unit for authorizing only data stations (ST) attached to a predetermined one of the bus segments connected to said active node unit, which said predetermined one segment then becomes theactive bus segment, to contend for access, transferring by each node unit messages from authorized data stations of the active bus segment, received on the one connected bus segment, to other connected bus segments in a flow direction away from the active bus segment, and passing the active node status from the currently active node unit to a predetermined next node unit, and repeating the above steps until all node units and bus segments were activated in a predetermined sequence.