Push vs. Pull: Implications of Protocol Design on Controlling Unwanted Traffic

In this paper we argue that the difficulties in controlling unwanted Internet traffic, such as email SPAM, stem from the fact that many Internet applications are fundamentally sender-driven and distinctly lack receiver control over traffic delivery. However, since only receivers know what they want to receive, receiver-driven approaches may often have clear advantages in restraining unwanted traffic. In this paper, we re-examine the implications of the two common traffic delivery models: sender-push and receiver-pull. In the sender-push model, a sender can deliver traffic at will to a receiver, who can only passively accept the traffic, such as in the SMTP-based email delivery system. In contrast, in the receiver-pull model, receivers can regulate if and when they wish to retrieve data, such as the HTTP-based web access system. We argue that the problem of unwanted Internet traffic can be mitigated to a great extent if the receiver-pull model is employed by Internet applications, whenever appropriate. Using three popular applications - email, mobile text messages, and asynchronous voice messages - as examples, we demonstrate that asynchronous communication protocols can be easily designed using the receiver-pull communication model to suppress unwanted Internet traffic.