Abstract: A dynamic synchronous transfer mode network that comprises two ring topologies having opposite fiber direction. The first dynamic synchronous transfer mode ring topology has a plurality of nodes for receiving and transmitting frames. The time slots are dynamically allocated to the nodes and the first ring topology is adapted to transmit frames only in a first fiber direction. The second dynamic synchronous transfer mode ring topology also has a plurality of nodes in common with the first ring topology. The second ring topology only transmits frames in a second direction that is opposite the first fiber direction.

Abstract: The dynamic synchronous transfer mode dual ring topology has two rings with opposite fiber directions. The dual rings may have a plurality of common nodes. A first channel may be established in a first segment extending between a first and second nodes. Tokens associated with the first channel may be provided. In this way, time slots may be transmitted in the first channel from the first node to the second node. If a fiber failure occurs in the first segment, the second node is likely to first detect the fiber failure and transmit a fiber failure message. It is then determined if the first channel extends across the fiber failure. If the first channel is affected by the fiber failure then a channel failure message is transmitted and the first channel is terminated and all the tokens associated with the first segment are removed. If the first channel is not affected then time slots are continued to be transmitted on the first channel.

Abstract: Idle messages are transmitted by an expansion node into the ring topology until the first idle message arrives to the expansion node after having passed through the entire ring. Frames may then be transmitted by the expansion node at every cycle time. The expansion node has an expansion buffer that may receive incoming frames and stores the frames until the next cycle time. The frame stored in the buffer may then be transferred to transmission side of the expansion node and transmitted into the ring topology. If there is no frame stored in the buffer at the beginning of a new cycle time, the expansion node may generate a new frame and transmit the new frame into the ring topology.