Vertical and Horizontal End-to-End Arguments in the Internet

We propose a novel taxonomy for the end-to-end arguments associated with the Internet: a vertical and horizontal version. While the former captures the trade-offs of where to place functions in a vertical network protocol stack, the latter deals with the trade-offs of spreading them across different hosts. Those two versions of the end-to-end argument were effectively one and the same in the early days of the Internet. However, this congruence is now thoroughly broken, and it is thus useful to separate the two conceptually. Primarily, this helps framing the broader debate on network design in light of tussles between the Internet's various stakeholders and higher order objectives such as user choice and fostering innovation.