Parallelism pervades the Internet, yet efficiently pooling this increasing path diversity has remained elusive. We defend that the inability to progress beyond a single path paradigm is due to an inflexible resource sharing model, rather than a lack of routing solutions. The tussle between networks and hosts over resource sharing has constricted resource pooling into being redefined by stakeholders according to their own needs, often at the expense of others. In this paper we debate existing

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... roaches to resource pooling and present PREFLEX, an architecture where edge networks and hosts both share the burden and reap the rewards of balancing traffic over multiple paths. Using PREF (Path RE-Feedback), networks suggest outbound paths to hosts, who in turn use LEX (Loss Exposure) to signal transport layer semantics such as loss and flow start to the underlying network. By making apparent network preferences and transport expectations, PREFLEX provides a mutualistic framework where congestion control and traffic engineering can both coexist and evolve independently.