  The primary task of a quantum repeater network is to deliver entanglement
among end nodes. Most of existing entanglement distribution protocols do not
consider purification, which is thus delegated to an upper layer. This is a
major drawback since, once an end-to-end entangled connection (or a portion
thereof) is established it cannot be purified if its fidelity (F) does not fall
within an interval bounded by Fmin (greater than 0.5) and Fmax (less than 1).
In this paper, we propose the Ranked Entanglement Distribution Protocol
(REDiP), a connection-oriented protocol that overcomes the above drawback. This
result was achieved by including in our protocol two mechanisms for carrying
out jointly purification and entanglement swapping. We use simulations to
investigate the impact of these mechanisms on the performance of a repeater
network, in terms of throughput and fidelity. Moreover, we show how REDiP can
easily be configured to implement custom entanglement swapping and purification
strategies, including (but not restricted to) those adopted in two recent
works.
