Formalization and configuration methodology for high-radix combined switches

Abstract

In large switch-based interconnection networks, increasing the switch radix results in a decrease in the total number of network components, and consequently the overall cost of the network can be significantly reduced. Moreover, high-radix switches are an attractive option to improve the network performance in terms of latency since hop count is also reduced. However, there are some difficulties related to integration scale to design such switches. In this paper we present and formalize an interesting alternative for building high-radix switches going beyond the integration scale bounds. The idea basically consists in combining several current smaller switches to obtain switches having greater number of ports. This strategy will remain valid as the scale of integration keeps evolving. Although simple, this strategy raises key design challenges in order to these high-radix switches achieve the best performance. The resultant internal structure of these switches becomes an important design decision, and an arbitrary selection may produce a significant performance degradation. For this reason, we also propose a general methodology to configure in an optimal way the internal switch structure and apply it to a particular case in order to show how it works. The resultant switch configurations are evaluated in order to show the real potential of our proposal.