J Supercomput (2012) 59:1–21 DOI 10.1007/s11227-010-0410-6 The 2D digraph-based NoCs: attractive alternatives to the 2D mesh NoCs Reza Sabbaghi-Nadooshan · Mehdi Modarressi · Hamid Sarbazi-Azad Published online: 17 March 2010 © Springer Science+Business Media, LLC 2010 Abstract This paper proposes two-dimensional directed graphs (or digraphs for short) as a promising alternative to the popular 2D mesh topology for networks-on- chip (NoCs). Mesh is the most popular topology for the NoCs, mainly due to its suitability for on-chip implementation and low cost. However, the fact that a digraph offers a lower diameter than its equivalent linear array of equal cost motivated us to evaluate digraphs as the underlying topology of NoCs. This paper introduces a family of NoC topologies based on three well-known digraphs, namely de Bruijn, shuffle- exchange, and Kautz. We study topological properties of the proposed topologies. We show that the proposed digraph-based topologies have several attractive features including constant node degree, low diameter and cost, and low zero load latency which result in superior performance over the mesh. We introduce a deadlock-free routing algorithm for the proposed NoC topologies and compare NoCs employing the proposed topologies and the mesh topology in terms of power consumption and R. Sabbaghi-Nadooshan Department of Electrical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran e-mail: r_sabbaghi@iauctb.ac.ir M. Modarressi · H. Sarbazi-Azad ( ) Department of Computer Engineering, Sharif University of Technology, Tehran,Iran e-mail: azad@sharif.edu M. Modarressi e-mail: modarressi@ce.sharif.edu M. Modarressi e-mail: modarressi@ipm.ir H. Sarbazi-Azad e-mail: azad@ipm.ir M. Modarressi · H. Sarbazi-Azad School of Computer Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran