Hi Ian, I am reading the ccid3 code for a while now and it seems to me that "the interval since the most recent packet loss event" is not taken into account while calculating I_mean, as you and Edgar suspect. The first interval used for calculating i_tot0 in dccp_li_hist_calc_i_mean() should point to "the interval since the most recent packet loss event", but it does not, I guess. In the morning I will debug this more and try to fix it, if all goes well. Actually I did some modifications today but they did not relieve my problems altogether. BTW, can you recommend me a tool for debugging the ccid (and dccp) module? I think there is Ostra but you seem to discourage its usage in the Ostra wiki page (http://wiki.linux.net.nz/Ostra). -- Burak Gorkemli Ph.D. Candidate Koc University Turkey ----- Original Message ---- From: Ian McDonald <ian.mcdonald@xxxxxxxxxxx> To: Edgar E. Iglesias <edgar.iglesias@xxxxxxxx> Cc: Burak Gorkemli <burakgmail-dccp@xxxxxxxxx>; dccp@xxxxxxxxxxxxxxx; DCCP mailing list <dccp@xxxxxxxx> Sent: Tuesday, August 29, 2006 2:38:09 AM Subject: Re: low tx speed in ccid3 after loss On 8/28/06, Edgar E. Iglesias <edgar.iglesias@xxxxxxxx> wrote: > Hi Ian, > > I beleive you need to recompute the loss rate on every received data packet. > While there is no packet loss, the average loss interval will increase and > p will decrease. > > This is because we take into account the interval between the lastest loss > event and the current sequence number if it helps us increase the rate. > > RFC 3448: > "When calculating the average loss interval we need to decide whether > to include the interval since the most recent packet loss event. We > only do this if it is sufficiently large to increase the average > loss interval." > > Without this, TFRC will never push the rate up to find newly added bw, unless > it is in slowstart ofcourse. > Thanks for this. I suspected that there would be something like this but I just didn't see it! At some stage I might code this up for the Linux implementation but I'm happy for somebody else to attempt (Burak?) as it's not affecting me right now. Ian -- Ian McDonald Web: http://wand.net.nz/~iam4 Blog: http://imcdnzl.blogspot.com WAND Network Research Group Department of Computer Science University of Waikato New Zealand
