| 摘要 |
A multi-star fiber optic network achieves improved access periods by grouping terminal devices into subnetworks that are connected to a bus, with token passing or collision detection being localized to individual subnetworks and with communication between subnetworks being conducted over the bus via non-interfering optical channels. The optical channels may be obtained by using light sources having different wavelengths or by modulating light at different channel frequencies. Each subnetwork includes an N-to-1 star which receives optical signals from terminal devices in the subnetwork and 1-to-N star which distributes optical signals to terminal devices in the subnetwork. Each subnetwork also includes a transmit repeater connected between the N-to-1 star and the bus to transmit messages which are addressed to other subnetworks on a unique channel, and a receive repeater connected between the bus and the 1-to-N star to receive messages on the channels assigned to other subnetworks. An electrical signal path connects the transmit repeater of a subnetwork with the receive repeater thereof to provide a signal path which does not utilize the bus. A buffer memory within the receive repeater of each subnetwork temporarily stores messages for subsequent distribution within the subnetwork. In order to avoid overloading any particular subnetwork when a token passing protocol is employed, for example, other subnetworks temporarily delay passage of the token when an outgoing message is generated. During this temporary delay messages stored in the buffer of the receive repeater are distributed.
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