Recursive Diagonal Torus (RDT) is a class of interconnection network consisting of recursively overlaid two-dimensional square diagonal tori for massively parallel computers with up to $2^{16}$ nodes. Connection structures of the RDT vary according to the assignment of upper rank diagonal tori into a node. Although traditional simple assignment called RDT(2,4,1)/$\alpha$ shows enough performance under the uniform traffic, the congestion of low rank tori degrades the performance when local communication is dominant.In this paper, RDT(2,4,1)/$\beta$ torus assignment is proposed, focusing on improving the performance for local communication. With a simplified simulation algorithm, result shows that RDT(2,4,1)/$\beta$ improves the average distance compared with RDT(2,4,1)/$\alpha$ assignment when considering local area.