| > 2. One minor thing where a clarification would be very helpful:
| > -> In section 4.6 "Preventing Oscillations"
| > -> Here it says "The sender obtains the base allowed transmit
rate,
| > X, from the throughput function."
| > -> But this is confusing, since the result of the throughput
| > function
| > is X_calc. Since the sender only gets a new R_sample when
it gets
| > feedback, is it meant that the sender obtains the allowed
sending
| > rate X as described in step (4) of section 4.3?
| I clarified that.
Could you please say what has been clarified? I found this section
very hard to
understand when starting to implement oscillation prevention. I only
really
understood its purpose after reading the corresponding section 3.6.4 of
Widmer's Diploma thesis (where he calls it `Inter-packet Space
Modulation', ISM).
I had revised the section somewhat, including a clarification that the
sender
obtains the allowed sending rate X as described in step (4) of section
4.3.
I just put the revised draft on my web site, and it is available from
"http://www.icir.org/floyd/papers/draft-ietf-dccp-rfc3448bis-02b.txt";.
There it became evident that oscillation prevention occurs as last
step before
computing t_nom: in the RFC this is not really clear.
The information I found was lacking in RFC 3448 is:
(1) Oscillation prevention is a step which follows immediately after
step (4)
of section 4.3, i.e. the reception of feedback packets. This is
the only
(sensible) place to perform oscillation prevention.
I have added that to the revised version.
(2) One needs to ensure that the TFRC minimum rates are not under-run
by doing
oscillation prevention (which is possible with integer arithmetic
when
sqrt(R_sample) > R_sqmean): something like
X_inst = X * R_sqmean / sqrt(R_sample)
/* where X is obtained as in step (4) of section 4.3 */
If (p > 0)
X_inst = max(X_inst, s/t_mbi)
Else if (not first feedback packet, or the first feedback
packet
after a nofeedback timer) {
X_inst = max(X_inst, s/R)
}
I added a slightly revised version of this. You can look at the revised
version, along with the revised version of Section 4.3, and see what you
think.
Many thanks,
- Sally
http://www.icir.org/floyd/
