Less-than-Best-Effort Service: A Survey of End-to-End Approaches

Abstract—This paper provides a survey of transport protocols and congestion control mechanisms that 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 and mechanisms provide what is sometimes called a less-than-best-effort or lower than best-effort service. To a user, such a service can, for instance, be an attractive choice for applications which create traffic that is considered less urgent than that of others—e.g., automatic backup, software updates running in the background, or peer-to-peer applications. The focus of this survey is on end-host approaches for achieving a less-than-best-effort service. This includes e.g. upper-layer methods, or techniques that leverage standard transport-layer mechanisms so as to reduce the impact on other competing flows. Index Terms—Transport protocols; congestion control; quality of service; less-than-best effort service. I