In which topology is the link between nodes unidirectional, so data travels one way only?

1. Common network topologies are mesh, ring, bus, star and tree. 2. In a ring, each node is joined to exactly two neighbours, one on either side. 3. The link in a ring topology is unidirectional. 4. Data therefore moves in one direction only, clockwise or counterclockwise. 5. In a bus, data passes along the length of the bus in both directions, and mesh and star both allow two-way links. _Source: syllabus Computer Science Class 12, Ch 10 'Computer Networks', S10.5.2 Ring Topology_