To be neutral or not neutral? The in-network caching dilemma

Caching strategies have been always regarded as an important tool to reduce network traffic and to guarantee an improved Quality of Service (QoS) to customers. However, being an inherently selective process, it results in service differentiation and, potentially, discriminatory treatment of user-requested content. Despite of this, in-network caching is not generally regarded as a traffic differentiation technique and, therefore, is not considered by Net-Neutrality (NN) regulations. In this paper, we look at this problem from a different perspective: the characteristics of today's Internet, such as the wide use of encryption, prevent Internet Service Providers (ISPs) from applying in-network caching without cooperating with Content Providers (CPs). Hence, a rigorous definition of NN-compliant caching is needed to agree upon the effective neutrality of ISPs. We compare different caching frameworks under the lens of NN and conclude that caching may lead to discrimination. Finally, we suggest a few research directions towards non-discriminatory in-network caching.