Subject: [Tsvwg] Response to Fred Baker on MLEF and MLPPoIP

From: "Steve Silverman" <[email-masked]>
Date: Tue, 9 Dec 2003 11:30:54 -0500

Someone called my attention to two IDs on the subject of
MLEF ( "MLEF Considered Harmful"  <draft-baker-tsvwg-mlef-
concerns-00>  (by Fred Baker and James Polk), and "Implementing
MLPP in the Internet Protocol Suite" <draft-baker-tsvwg-
mlpp-that-works-00> by Fred Baker.  Sorry it has taken so long to
respond
but personal issues related to a snowstorm have kept me
otherwise occupied.

MLEF is not mutually exclusive with a CAC.  I think they
provide complimentary functionality.

As Fred points out, in some situations, more bandwidth can
NOT be deployed easily.  Therefore, silence suppression (or
Voice Activity Detection), which will provide two to three
times more voice channels in a fixed amount of bandwidth,
may be a necessary function even if it limits the precision
of the CAC.  MLEF can guarantee that the critical calls get
thru short periods of congestion.

Much was made in "MLEF Considered Harmful" of the impact of
MLEF on ILBC.  I do not know of any use of this codec in
the DOD.  I would hope that a better choice would be make
for a VoIP codec.

MLEF does NOT introduce a delay into packet flow.  When
congestion occurs, some packets (from the lowest priority
class) are dropped.  This allows the higher priority
packets to proceed thru the bottleneck faster.

I never claimed that MLEF is a complete solution to the
issue of VoIP congestion.  Call Control was not considered
in this work.  It dealt solely with a PHB that would act at the packet
level.
Since we had limited funding, I
picked one aspect of the problem (a PHB) that I thought I
could do within a limited time frame.  I felt that this was one key
issue
that required additional analysis. Other people were already
working on Call Control.  I have always said that
considerable additional work was needed.

Steve Silverman

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