Editing Scalable Coherent Interface (section)

===Topologies===
SCI can be used to build systems with different types of switching topologies from centralized to fully distributed switching:

*With a central switch, each node is connected to the switch with a ringlet (in this case a two-node ring). 
*In distributed switching systems, each node can be connected to a ring of arbitrary length and either all or some of the nodes can be connected to two or more rings. 

The most common way to describe these multi-dimensional topologies is k-ary n-cubes (or tori). The SCI standard specification mentions several such topologies as examples.

The 2-D [[torus]] is a combination of rings in two dimensions. Switching between the two dimensions requires a small switching capability in the node. This can be expanded to three or more dimensions. The concept of folding rings can also be applied to the Torus topologies to avoid any long connection segments.