The Growth of Internet Overlay Networks: Implications for Architecture, Industry Structure and Policy

Over the past several years, we have seen the emergence of numerous types of socalled "overlay" networks in the Internet. There are many diverse examples of such overlay networks including the content-delivery-caching networks, implemented by companies like Akamai, the peer-to-peer file sharing networks associated with applications such as BitTorrent, the voice-over-IP services offered via Skype, and various testbed networks such as PlanetLab. These overlay networks enhance or modify the basic functioning of traffic handling within the Internet. Overlays exist in the blurry boundary between what we think of as "the Internet" (a globally interconnected network of IP networks) and the applications that exist on top of the Internet. Overlays also blur the boundaries between the network edges (what we think of as being associated with customer end-nodes) and the network core (what we think of as associated with the services that support the Internet). As such, overlays have important technological and policy implications for the evolution of next generation Internet architecture that historically has been based on the so-called "end-to-end" principle ([SRC84], [BC01]) which relied on a relatively clear demarcation between applications and network services, and edge and core responsibilities. Because of the Internet's growing role as basic infrastructure and increasingly central role in the communications industry, and hence, obvious focus for regulation, changes in Internet architecture have important policy and industry structure implications. For example, from a regulatory perspective, the debate over overlays in Internet-space is analogous to the on-going debate over "layered regulation" (see [Fre02], [Sic02], [Wer02]) and how one might distinguish between "basic telecom services" (which may be regulated under Title II as 1 Bill Lehr is the corresponding author for this paper ([email protected]).