Communication system comprising overlayed multiple-access transmission networks

Communication system comprising a first data transmission network (11) for small-volume data transfers and a separate second data transmission network (13) for high-speed large-volume data transfers, characterized in that

• said second network (13) is an optical fiber transmission network and comprises access nodes (23) each for attaching a group of stations (21), that
• common optical output means (45, 47) are provided at each said access node for transferring optical data signals directly from the second network in parallel to stations of the respective group, that
• optical input means (53, 55) are provided at each said access node for transferring optical data signals from any of the attached stations to said second network, and that
• means are provided in each said station (101, 145) for receiving access information from said first network for controlling data transfers from the respective station to said second network in response to said access information.

In a communication system comprising two separate networks (11, 13) each for transferring data between stations (17, 21) attached to the respective network, a method for regulating data transmission access to one of said networks (13), comprising the steps of

• receiving access information at one network (13) from stations attached to it and then transmitting access information to the other (11) of said two networks, whereby access information for said one network (13) is transferred only over said other network (11);
• issuing tokens of at least a first and a second kind on said other network (11) by a token manager (27) wherein said token manager (27) regulates access to said one network (13) and said other network (11), respectively;
• issuing a first kind token from said token manager (27) with the same status (busy/free) as the last such token had when returning to the token manager (27) wherein said first kind token circulates through all stations and returns to the token manager which stores its status;
• changing the next first kind of token that said station manager (27) receives free to busy, forwarding it on the other network (11) and starting transmission on the one network (13) when stations want to transmit on the one network (13);
• changing the next first kind of token said station manager (27) receives busy to free and forwarding it on the other network (11) when stations want to end a transmission on the one network (13);
• whereby during the time interval while a station (21) is transmitting on the one network (13) a first kind of token may be circulating on the other network (11) in a busy status without being changed.