Re: RDT specifications

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Hi,
 
I contact you because I don't find any clear documentation about the rate adaptation mechanism I observe on my network.
Here is a short description of my problem.
I'm analysing my network performances on streaming applications over RDT/UDP. The public backbone as no throughput restriction, my private network is limited to 32kb/s in uplink and downlink. I'm trying to watch a video encoded with 100kb/s using streaming RDT/UDP. I repeat 10 times the same scenario in the same conditions, 8 times out of 10 attemps I observe the behaviour "A" and 75% of the packets lost, and the 2 attemps left I observe the behaviour "B" and 65% lost.
- behaviour "A" : the throughput on the backbone side stays at 150kb/s during all the transfer, the client reports ACK every second and NACK for each message missing.
- behaviour "B" : the throughput is 150kb/s, the client reports ACK every second and NACK for each missing message (like for ";A") but only during the first 15 seconds of the transfer, then the client stops sending both ACK and NACK and the data rate on the backbone side slows down to 100kb/s until the end of the transfer (why ?!).
 
Do you have any idea of what happens or any suggestion of documentation I could read to investigate the cause of this.
 
Thanks for your help
 
Regards
Vincent
 
 

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De : Rishi Mathew [ rmathewreal.com" eudora="autourl"> mailto:rmathewreal.com]
Envoyé : lundi 10 mars 2008 16:39
À : zze-EQOS LEMAIRE V ext RD-RESA-ISS
Cc : protocol-devhelixcommunity.org
Objet : Re: [hxadmin] RDT specifications

Hi Vincent,

RDT v1 was deprecated a while back and completely replaced by v2&v3. There should be no servers in the market today using v1.

If you are seeing some kind of rate adaptation mechanism as you mention, then the client/server is using v3 (which was when rate adaptation was introduced).

I have cc'ed the mailing list where you can ask further questions.

Cheers,
Rishi.

At 11:37 PM 3/9/2008, vlemaire.extorange-ftgroup.com wrote:

Hello,

I'm currently analysing my network performances on streaming applications over RDT/UDP. I observe a strange behaviour : sometimes the throughput slows down, sometimes not. I really guess the data rate reduction is due to RDT layer, probably because of bad performances of my network, to investigate what causes this RDT reaction, I need the RDT specification, but only RDT v2 and v3 features' description are available on your web site. Do you know where and how could I get the RDT spec V1.

Thanks

Best regards

Vincent

Rishi Mathew
Helix Community
Real Networks, Inc.
rmathewreal.com
http://www.helixcommunity.org
http://www.realnetworks.com/products/support/devsupport.html
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