**** Columbia Network Research Group Seminar ****

Title:    Some Observations on Equation-Based Rate Control
Speaker:  Milan Vojnovic
          EPFL & Lucent 
When:     Wednesday, September 19, 2001 - 2 pm
Where:    Interschool Lab
          Seventh Floor, CEPSR building
          Columbia University
Host:     Prof. H. Schulzrinne

ABSTRACT

We consider a general problem of unicast equation-based rate control
in the Internet, which we formulate as follows. When a so called
"loss-event" occurs, a data source updates its sending rate by setting
it to f(p_n), where p_n is an estimate of p, the long-run loss event
ratio. Function f (the target loss-throughput function) defines the
objective of the control method: we would like that the throughput x,
attained by the source, satisfies the equation x<=f(p). If so, we say
that the control is conservative. In the Internet, function f is
obtained by analyzing the throughput versus loss-event ratio for a
real TCP source. A non-TCP source that implements a control system as
we describe is said to be TCP-friendly if the control is conservative.

Our main finding are two sufficient conditions under which the control
is provably conservative. As a by-product, we explain an empirically
observed phenomena that the throughput deviates in the conservative
direction as the loss-event ratio tends to be large.

This is joint work with Jean-Yves Le Boudec.