Subject: Re: [iccrg] AIMD versus AIAD

From: "K. K. Ramakrishnan" <[email-masked]>
Date: Fri, 20 Nov 2020 07:40:37 -0800

Folks,

When we were working on the DECbit work (ECN has many similarities), we 
focused on the unit of time over which all the competing flows modified 
their demand so as to eventually converge to a fair and efficient 
operating point, independent of where they started from.

The fairness consideration was based on the action taken by each source 
over that unit of time, which based on the feedback control system model 
we had informally in our mind, was the dominant RTT. Rather than 
focusing on the action at the source on each individual packet/ack, 
since we know that each source could potentially have fewer or more 
packets in that unit of time, we look at the control action over an RTT, 
even if on each ack. the source took small steps. I used to think in 
similar terms as Aurel Lazar had been with their bang-bang flow control 
work.

So, the amount of increase and decrease we were looking at was over the 
dominant RTT (maybe we should have focused more on RTT heterogeneity 
then, but that came a bit later, when we looked at Selective Feedback 
(DEC TR 508), but that is another matter...).

Thanks,

  K. K. Ramakrishnan

-- 
K. K. Ramakrishnan
Professor
Dept. of Computer Science and Engineering
University of California, Riverside
Rm. 332, Winston Chung Hall
Tel: (951) 827-2480
Web Page: http://www.cs.ucr.edu/~kk/