Distinguish between green and black links in a dragonfly group
Cray dragonflies have two type of intra-group links i.e. green and blue. Both links are electrical and have a bandwidth of 5.25 GiB/s but for green links connecting Aries within the same chassis, there is one cable between the Aries router. For black links connecting Aries among different chassis, there are 3 cables which means additional bandwidth for Aries connecting different chassis. We need to distinguish these two types of links in the simulation to model the right link bandwidths.