  Entanglement routing in near-term quantum networks consists of choosing the
optimal sequence of short-range entanglements to combine through swapping
operations to establish end-to-end entanglement between two distant nodes.
Similar to traditional routing technologies, a quantum routing protocol uses
network information to choose the best paths to satisfy a set of end-to-end
entanglement requests. However, in addition to network state information, a
quantum routing protocol must also take into account the requested entanglement
fidelity, the probabilistic nature of swapping operations, and the short
lifetime of entangled states. In this work, we formulate a practical
entanglement routing problem and analyze and categorize the main approaches to
address it, drawing comparisons to, and inspiration from, classical network
routing strategies where applicable. We classify and discuss the studied
quantum routing schemes into reactive, proactive, opportunistic, and virtual
routing
