Cost-Efficient Dragonfly Topology for Large-Scale Systems

It is more efficient to use increasing pin bandwidth by creating high-radix routers with a large number of narrow ports instead of low-radix routers with fewer wide ports. building networks using high-radix routers lowers cost and improves performance, but also presents many challenges. the dragonfly topology minimizes network cost by reducing the number of global channels required.

Dragonfly Topology

Topology is a critical aspect of any interconnection network because it sets performance bounds for the network by establishing the network diameter and bisection bandwidth. The topology also largely determines the system's cost, in terms of both capital and energy consumption―thus, using a cost-efficient network topology is critical. Existing topologies, such as folded-Clos and fat-tree, pay too high a penalty on load-balanced traffic (for example, uniform random) to provide good performance in an adversarial traffic pattern. In essence, they consume costly bandwidth to load-balance traffic that is already balanced.