[Codel] why RED is not considered as a solution to bufferbloat.

Wesley Eddy wes at mti-systems.com
Tue Feb 24 11:27:19 EST 2015

On 2/24/2015 10:37 AM, sahil grover wrote:
> (i) First of all,i want to know whether RED was implemented or not? 
> if not then what were the reasons(major) ?
> anyone please tell me in simple words here only,because i don't want to
> read any paper like "RED in a different light".
> (ii)Second, as we all know RED controls the  average queue size from
> growing.
> So it also controls delay in a way or  we can say  is a solution to
> bufferbloat problem. Then why it was not considered.

There is an IETF document from the AQM working group which contains
some discussion towards your first question, at least:
(this should be published as an RFC "soon")

Specifically, the text says:

   With an appropriate set of parameters, RED is an effective algorithm.
   However, dynamically predicting this set of parameters was found to
   be difficult.  As a result, RED has not been enabled by default, and
   its present use in the Internet is limited.  Other AQM algorithms
   have been developed since RC2309 was published, some of which are
   self-tuning within a range of applicability.  Hence, while this memo
   continues to recommend the deployment of AQM, it no longer recommends
   that RED or any other specific algorithm is used as a default;
   instead it provides recommendations on how to select appropriate
   algorithms and that a recommended algorithm is able to automate any
   required tuning for common deployment scenarios.

Wes Eddy
MTI Systems

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