Hi,

I'm a student in network and I make a research on Date Center architecture. I've reached the point where I realized that Fat-tree seems to be the most used topology, (Google, Facebook...) but i observed it is worst in terms of Scale, Bandwidth, Fault-tolerance Scalability, Cost compared to DCell or JellyFish as an example, do you know why we use it so much?

I also read that SDN are changing this optic it is real ?

Thank for your help