Low Extra Delay Background Transport (LEDBAT)
RFC 6817

Approval announcement
Draft of message to be sent after approval:

From: The IESG <iesg-secretary@ietf.org>
To: IETF-Announce <ietf-announce@ietf.org>
Cc: RFC Editor <rfc-editor@rfc-editor.org>,
    ledbat mailing list <ledbat@ietf.org>,
    ledbat chair <ledbat-chairs@tools.ietf.org>
Subject: Document Action: 'Low Extra Delay Background Transport (LEDBAT)' to Experimental RFC (draft-ietf-ledbat-congestion-10.txt)

The IESG has approved the following document:
- 'Low Extra Delay Background Transport (LEDBAT)'
  (draft-ietf-ledbat-congestion-10.txt) as Experimental RFC

This document is the product of the Low Extra Delay Background Transport
Working Group.

The IESG contact persons are Wesley Eddy and Martin Stiemerling.

A URL of this Internet Draft is:

Technical Summary

This document describes an experimental congestion algorithm for building a
lower than best-effort transport. The algorithm attempts to use the residual
capacity on an end-to-end path while limiting queuing delay. The algorithm sense
increase in one-way delay measurements to yield in the presence of any competing
flows thus limiting interference with the network performance of competing

Working Group Summary
We reached consensus on the basic algorithm a long while back while most of the
later revisions and discussions were around parameterization and choosing the
right defaults. This is expected as this is an experimental algorithm and data
needs to guide these decisions rather than theory. In the end we got enough
(independent) experimental data that guided the design decisions.

Document Quality
There are several independent implementations including BitTorrent itself which
pioneered this algorithm and ship it in their product. A number of universities
and more recently Apple prototyped and shared results during the last call. I am
confident that parameterization and associated tradeoffs are well understood and


Murari Sridharan (muraris@microsoft.com) is the document shepherd.
Wesley Eddy (wes@mti-systems.com) is the responsible AD.