Subject: [ledbat] Confirmation: Call for Adoption of "Low Extra Delay Background Transport" as a LEDBAT WG work item

From: Bernard Aboba <[email-masked]>
Date: Wed, 29 Jul 2009 05:27:18 -0700

During the IETF 75 LEDBAT WG meeting, the attendees indicated an interest in adopting "Low Extra Delay Background Transport" (draft-shulanov-ledbat-congestion) as a LEDBAT WG work item (with Experimental status).  

We would now like to verify the outcome of this call for adoption on the LEDBAT WG mailing list.  The document is available for inspection here:

http://tools.ietf.org/html/draft-shulanov-ledbat-congestion

If you did not raise your hand at the IETF 75 LEDBAT WG meeting, and have an opinion as to the suitability of adopting this document as a WG work item, please send mail to the LEDBAT WG list indicating your opinion (Yes/No/Abstain). 

The confirmation call for adoption will last until August 7, 2009.  If you have issues/edits/comments on the document, please send these comments along to the list in your response to this Call for Adoption. 

Bernard

Acting WG Co-Chair

 EMAILING FOR THE GREATER GOOD
Join me

---

From: "Eddy, Wesley M. (GRC-MS00)[Verizon]" <[email-masked]>
Date: Thu, 30 Jul 2009 11:17:25 -0500

I supported adoption of this draft in the WG meeting, and
will support it again on the list, though I'll be very clear
that it still needs some work.  It is a good start.  I've
read it a couple of times, and have a few comments:

Technical Comments:

1 -
Similar to RFC 2581, a "FlightSize" should be defined for the amount
of data in flight, since it's not always the same as cwnd.  This can
(and has) lead to errors in TCP implementation, so it should be made
clear.

2 -
"halve on loss" ... this should refer to the FlightSize rather than
the window, consistent with RFC 2581.

3 -
TARGET of 25 ms seems arbitrary for a "MUST" ... I think it should be
a default constant via "SHOULD", but could be ripe for experimentation.

4 -
should the NOISE_FILTER be related to cwnd or FlightSize? ... I think
FlightSize.

5 -
Definition of how loss is detected in order to generate a cwnd reduction
is absolutely required.  This needs to be clear and prominent in the
draft.

6 -
Is it correct that this is not intended to be an "ECN-Capable Transport"?
It seems like ECN could be added ... it's listed as a design goal, but not
accommodated by the algorithm specification itself.

Editorial Comments :

1 - 
In section 2, Introduction (first sentence)

   The standard congestion control in TCP is based on loss and has not
   been designed to drive delay to any given value.  Because TCP needs
   losses to back off, when a FIFO bottleneck lacks AQM, TCP fills the
   buffer, effectively maximizing possible delay.

there are a couple problems with precision in this, suggest changing to ->

   The standard TCP congestion control algorithms [RFC2581bis] are
   based on congestion signals that do not directly include queueing
   delay.  Without Active Queue Management (AQM), TCP fills buffers
   at bottlenecks within the network [RFC2309], effectively creating
   maximal queueing delay at the bottleneck.

2 -
Abstract & Introduction "advanced networking applications" should just
be "applications"

3 -
several places require disambiguation of "delay" into "queueing delay"

4 -
overall, there could be some slight grammatical improvements in a lot
of places, but I'd wait until the document is near WGLC to worry about
them.

---------------------------
Wes Eddy
Network & Systems Architect
Verizon FNS / NASA GRC
Office: (216) 433-6682
---------------------------

>-----Original Message-----
>From: [email-masked] [mailto:[email-masked]] On Behalf
>Of Bernard Aboba
>Sent: Wednesday, July 29, 2009 8:27 AM
>To: [email-masked]
>Subject: [ledbat] Confirmation: Call for Adoption of "Low Extra Delay
>Background Transport" as a LEDBAT WG work item
>
>
>During the IETF 75 LEDBAT WG meeting, the attendees indicated an
>interest in adopting "Low Extra Delay Background Transport" (draft-
>shulanov-ledbat-congestion) as a LEDBAT WG work item (with Experimental
>status).
>
>We would now like to verify the outcome of this call for adoption on the
>LEDBAT WG mailing list.  The document is available for inspection here:
>If you did not raise your hand at the IETF 75 LEDBAT WG meeting, and
>have an opinion as to the suitability of adopting this document as a WG
>work item, please send mail to the LEDBAT WG list indicating your
>opinion (Yes/No/Abstain).
>
>The confirmation call for adoption will last until August 7, 2009.  If
>you have issues/edits/comments on the document, please send these
>comments along to the list in your response to this Call for Adoption.
>
>Bernard
>Acting WG Co-Chair
>
>
>
>
>
>i'm EMAILING FOR THE GREATER GOOD
>Join me
><http://im.live.com/Messenger/IM/Home/?source=EML_WLHM_GreaterGood>