A Lower Than Best-Effort Per-Hop Behavior

Document Type Expired Internet-Draft (individual)
Authors Roland Bless  , Klaus Wehrle 
Last updated 1999-09-08
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document describes a Lower than Best-Effort (LBE) per-hop behavior (PHB) for use within and between Differentiated Services domains [3]. The primary objective of this LBE PHB is to separate LBE traffic from best-effort traffic in congestion situations, i.e., when resources become scarce. Furthermore, LBE traffic gets a minimal share of bandwidth so that it will not be fully preempted by best-effort traffic. This is achieved by discarding LBE packets more aggressively than best-effort packets while trying to enqueue them in case of congestion. There are numerous uses for this PHB, e.g., for transmission of background traffic such as bulk data transfers of minor importance, backup data traffic during working hours or traffic caused by web search engines while gathering information from web servers. Thus, it constitutes the network equivalent to a background priority for processes in an operating system. Moreover, it is particularly useful in cases when packets of a better service are re-marked by a node for subsequently receiving a forwarding treatment that is equivalent to the best-effort service. In this situation the LBE PHB helps to protect other best-effort packets from experiencing unfair forwarding treatment because it avoids their preemption by re-marked packets. For instance, this case occurs when heterogeneous multicast groups should be supported.


Roland Bless (bless@telematik.informatik.uni-karlsruhe.de)
Klaus Wehrle (wehrle@telematik.informatik.uni-karlsruhe.de)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)