are more cost efficient. Evolving hardware ecosystem: Over a period of about 5 years, the cost of packet switching has dropped an order of magnitude, from $10,000 per 10GigE port in 2010 to $100 per 10GigE port in 2015 and these costs continue to drop. This is very material to a network operator because cus- tomer bandwidth continues to grow exponentially while the revenue associated with this bandwidth changes linearly. In our observation, there are five main drivers for why there has been a three order of mag- nitude drop in cost. The first is Moore's Law and advances in silicon technology. The second is new merchant silicon competitors in the marketplace that aggressively compete against custom silicon offerings from traditional original equipment manufacturer (OEM) suppliers. The third is simplification in switching features provided by merchant silicon entrants that result in increased packet switching throughput. The fourth is disaggregation of vertical packet switch/router plat- forms from traditional OEMs into separable software and hardware modules. And, the fifth is high volume commoditization with merchant silicon by Web 2.0 companies leading to economies of scale. Network Edge The tremendous technological progress encapsulated in Moore's law is well documented else- where (Moore 2015). The other drivers deserve further comment as they shed light on architectural considerations discussed in this chapter. Merchant silicon: Packet switching silicon can be classified into three broad categories based on a matrix of features versus throughput. Custom silicon is rich with features but has lower through- put per chip and has the highest cost per bit because of the number of chips required in a Clos architecture for equivalent throughput. Custom silicon for packet switching is only available by purchasing vertically integrated products from OEMs. At the opposite end of the spectrum is data center merchant silicon with very limited features or flexibility but with the highest throughput per chip and the lowest