Edge-Disjoint Spanning Trees on the Star Network with Applications to Fault Tolerance

• Authors: Paraskevi Fragopoulou;Selim G. Akl
• Venue: IEEE Transactions on Computers
• Year: 1996

Data communication and fault tolerance are important issues in parallel computers in which the processors are interconnected according to a specific topology. One way to achieve fault tolerant interprocessor communication is by exploiting and effectively utilizing the disjoint paths that exist between pairs of source and destination nodes. In this paper, we construct n - 1 directed edge-disjoint spanning trees, on the star network. These spanning trees are used to derive a near optimal single-node broadcasting algorithm, and fault tolerant algorithms for the single-node and multinode broadcasting, and for the single-node and multinode scattering problems. Broadcasting is the distribution of the same group of messages from one processor to all the other processors. Scattering is the distribution of distinct groups of messages from one processor to all the other processors. We consider broadcasting and scattering from a single processor of the network and simultaneously from all processors of the network. The single-node broadcasting algorithm offers a speed up of n - 1 for a large number of messages, over the straightforward algorithm that uses a single shortest path spanning tree. Fault tolerance is achieved by transmitting the same messages through a number of edge-disjoint spanning trees. The fault tolerant algorithms operate successfully in the presence of up to n - 2 faulty nodes or edges in the network. The degree of fault tolerance can be adjusted depending on the network reliability. The importance of this method lies in the fact that no prior knowledge of the faulty nodes or edges is required. All of the algorithms operate under the store-and-forward, all-port communication model.