Dear Emmanuel, That's interesting to know. What was the target application? I would be interested to see the results. Regards Arjuna > -----Original Message----- > From: Emmanuel Lochin [mailto:emmanuel.lochin@xxxxxxxxx] > Sent: 16 August 2007 22:31 > To: Arjuna Sathiaseelan > Cc: Ingemar Johansson S (LU/EAB); 'dccp' working group; Gorry Fairhurst; > Golam Sarwar; Roksana Boreli; Sebastien Ardon; Guillaume Jourjon > Subject: Re: DCCP for VoIP > > Hi Arujna, > > I have a question concerning the following point: > > On 16/08/07, Arjuna Sathiaseelan <arjuna@xxxxxxxxxxxxxx> wrote: > > > 2) How often is feedback sent? (sorry for a qu estion that I should > > > probably answer myself by means of some RTFM) but if you could answer > it I > > > would really appreciate it. > > > > Usually CCIDs incorporating the TFRC or TFRC-SP protocol would send a > > feedback once per RTT, unless there is a change in the loss event. If > there > > is a change in the loss event then the feedback would be sent > immediately. > > Alternatively these protocols could send multiple feedbacks per RTT > (when > > there is no change in the loss event) but it is not a common practice in > my > > opinion. > > I am wondering why this is not a common practice? > > We (Golam, Roksana and me, in copy of this email) are currently evaluating > GNU/Linux DCCP/CCID3 over over live satellite and long range wireless > links. > > As expected, DCCP/CCID3 obtains poor performance compared to TCP. > In a logical way, on such long delay networks, the feedback loop is linked > to the delay of the connection and thus, cannot update the transmitted > rate as efficiently as over a low delay network. > > However, if we increase the number of feedback messages as a function > of the RTT over these long delay networks, DCCP/CCID3 performance are > really better. This has been verified in ns-2.30 and over satellite > and Wimax networks. As a result, we are currently considering a > dynamic algorithm for adjusting the amount of DCCP feedback based on > RTT. > > Emmanuel > > > -- > Emmanuel Lochin http://mobqos.ee.unsw.edu.au/~lochin/ > Networks and Pervasive Computing Research Program > National ICT Australia Ltd > Locked Bag 9013, Alexandria, NSW 1435 > Australia > --- > "This email and any attachments are confidential. They may contain legally > privileged information or copyright material. You should not read, copy, > use > or disclose them without authorisation. If you are not an intended > recipient, please contact us at once by return email and then delete both > messages. We do not accept liability in connection with computer virus, > data corruption, delay, interruption, unauthorised access or unauthorised > amendment. This notice should not be removed"
