The author states:
"Yet, most routers still support a 100ms+ buffer depth for 100GB/s circuits. Just do the math. You need 1.25 GB DDR4 RAM for each 100GB/s port in a given router."
What is the math? It's not clear at all how he arrived at that calculation. That seems like quite an important detail to omit in your first supporting paragraph. Just saying "just do the math" when its not clear what that is is a bit ridiculous.