From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bruce Barnett Date: Tue, 20 Dec 2005 17:38:16 +0000 Subject: Re: Discussion of ECN API? Message-Id: <200512201738.jBKHcGm15341@observ.crd.ge.COM> List-Id: References: <200512192127.jBJLRou27403@observ.crd.ge.COM> In-Reply-To: <200512192127.jBJLRou27403@observ.crd.ge.COM> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: dccp@vger.kernel.org > I'm not aware of any, at the same time I think DCCP should at least > expose the info on ack vectors,so the question is: is the information > available on ack vectors enough for you (the app writers?)? Raw information may be harder to deal with, but at least all of the information is there. After we have a better idea on the algorithms needed for intelligent applications, we can provide a friendlier interface. I don't think we know the best algorithms yet. I think DCCP-enabled applications that are aware of congestion are key to the next generation of streaming networking. TCP-based applications don't care if the network is congested. Either the data arrives or it doesn't. but VoIP/DCCP applications need to deal with latency and reliability, and if quality drops, they must take responsibility. Consider a VoIP application with a 10% packet loss. With some vocoders, a 10% loss is unintelligable. So the application is sending out 90% of the packets with zero effectiveness. Those packets are useless, yet they are contributing to the congestion. I view this as abuse to the network in two ways (1) sending out packets that are contributing to congestion, and (2) doing so in such a way that the packets are useless once they arrive. TCP doesn't abuse the network like this. Likewise, if the reliability was high, but the latency increased to 2 seconds per packet, then the usefullness of the bandwidth also decreases as the mouth-to-ear delay increases. Application adaption is key to minimizing network abuse for streaming applications like VoIP. Now we just have to figure out how to do it the right way. :-)