A method for line-plane broadcasting in a data communications network of a parallel computer, the parallel computer comprising a plurality of compute nodes connected together through the data communications network and through another data communications network, the data communications network optimized for point to point data communications, the another data communications network optimized for collective operations, the data communications network organized in a rectangular mesh topology and characterized by a first dimension, a second dimension, and a third dimension, the method further comprising
- partitioning, by a broadcasting compute node, a message into a plurality of portions, each portion corresponding to one of the dimensions;
- initiating, by the broadcasting compute node, a broadcast operation, including sending the portion of the message that corresponds to the first dimension to all of the compute nodes along an axis of the first dimension for the data communications network;
- sending, by each compute node along the axis of the first dimension, the portion of the message that corresponds to the first dimension to all of the compute nodes along an axis of the second dimension for the data communications network;
- and
- sending, by each compute node along the axis of the second dimension, the portion of the message that corresponds to the first dimension to all of the compute nodes along an axis of the third dimension for the data communications network,
- wherein the plurality of compute nodes are organized into at least one operational group and wherein the line plane broadcasting in the data communications network is carried out using only the compute nodes in the operational group.