What is the problem? Is the problem real?
Using high end interconnects like Infiniband and Myranet is too expensive so we want to build Datacenter networks out of commodity switches and routers.
What is the solution’s main idea (nugget)?
They design a fat tree network architecture for the datacenter entirely out of low cost commodity components with the scaling, economic, and backward compatibility properties that we desire.
Why is solution different from previous work? (Is technology different?, Is workload different?, Is problem different?)
I believe that the use of fat trees in the data center is a very old idea.
Here is a blog post I wrote last semster about a talk on this research that Amin Vahdat came and gave at the weekly Berkeley systems seminar.