A survey of lower-than-best-effort transport protocols. RFC 6297, IETF.
Résumé
This document provides a survey of transport protocols which are designed to have a smaller bandwidth and/or delay impact on standard TCP than standard TCP itself when they share a bottleneck with it. Such protocols could be used for low-priority "background" traffic, as they provide what is sometimes called a "less than" (or "lower than") best-effort service.