SDN allows us to make bold new choices for Layer 3 routing, and Layer 2 circuit implementation. Both of these layers ride on an underlying Layer 1 / Layer 0 transport network. In this talk we will examine our choices for each of these protocol layers, and the implications of certain combinations of L0-L3 SDN stacks. These include ideas such as Core-Router offload, Edge-Router offload, centralized path computation, routing, QoS, and network resilience. As well we will examine the readiness of SDN implementations for these new ideas, and identify areas that require further work.