Subject: Re: [Tsvwg] SCTP Max.burst and CWND

From: Mark Allman <[email-masked]>
Date: Tue, 05 Mar 2002 22:44:34 -0500

> Looks good to me! So now, Max.Burst is just a parameter to your
> algorithm, which in your example is 4.

Right.  It is not a control itself, but rather a piece of the cwnd
control. 

> Also, this algorithm should be applied _all_ the time. 

Yep.

And, to be clear -- what I outlined is not a new idea.  It is
basically use-or-lose (or a variant thereof).  Joe Touch has thought
about and posted about this sort of thing.  And, RFC 2861 has some
of these sorts of notions, I think.  All of these folks Got It
before I did...I've just now caught up!

> Yes, there are only 3 scenarios (that I know of) when bursts are
> likely:
> 
> 	1. after FR recovery
> 	2. after idle periods
> 	3. sender goes from application-limited to network-limited

The fix I sketched works for all of these cases, I think.  That is,
you can never store more than some small amount of permission to
send.  If cwnd grows to more than your outstanding data + a fudge
factor you reign in cwnd.

There is a fourth case of bursting that I outlined the other day...
That happens when you lose bunches of ACKs.  I am not sure what the
right answer there is...

allman

---
Mark Allman -- NASA GRC/BBN -- http://roland.grc.nasa.gov/~mallman/

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From: "Armando L. Caro Jr." <[email-masked]>
Date: Wed, 6 Mar 2002 08:59:29 -0500 (EST)

> And, to be clear -- what I outlined is not a new idea.  It is

point noted.

> before I did...I've just now caught up!

me too :-)

> factor you reign in cwnd.

yes, you are right. didn't realize that in my quick reply yesterday.

> There is a fourth case of bursting that I outlined the other day...

yeah, forgot about that one...

> That happens when you lose bunches of ACKs.  I am not sure what the

well we can put a little more thought into this one before spitting out a
solution.

~armando

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| Armando L. Caro Jr.     |       [email-masked] |
| University of Delaware  |  www.cis.udel.edu/~acaro |
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