Date: Thu, 07 Dec 2006 10:35:32 +0900 From: gnn@freebsd.org To: "maillist ifiaas" <maillist.ifiaas@gmail.com> Cc: freebsd-net@freebsd.org Subject: Re: Urel, a TCP option for Unreliable Streaming. Need your help. Message-ID: <m21wncv66z.wl%gnn@neville-neil.com> In-Reply-To: <161d69110612060709n3bf99bd4y47d94b021b8f1d02@mail.gmail.com> References: <161d69110612060709n3bf99bd4y47d94b021b8f1d02@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
At Wed, 6 Dec 2006 23:09:39 +0800, maillist ifiaas wrote: > > Hi friends, > > This is one of my research project. Our purpose is to modify TCP to > support unreliable but congestion controlled streaming. The > motivation is pretty similar to the one of DCCP CCID2. We have > implemented a prototype on FreeBSD 5.4, and the the modifications > are limited mostly in tcp_input.c and tcp_output.c. Source code, a > paper about the design (under submission), and an Iperf modification > to test out TCP Urel, is provided on the following page: > www.comp.nus.edu.sg/~malin/ > > Our current stage is changing Urel into a single directional > streaming protocol, so taht it could be abosolutely fair with > default TCP Sack, in FreeBSD. But we found after all the > modifications (on single directional streaming), Urel generates less > ACK than normal Sack, making it under utilized when competing to TCP > Sack. About only 3 out of 10 tries, Urel take the same throughput as > Sack. The reason seems to lying in the Delay ACK code, in > tcp_input.c. Because, when we turn off the Delay ACK option, using > sysctl command, Urel and Sack play fairly. However after days of > looking at the code, we failed to find the secret... Therefore, I > turn to you, the specialists of the TCP code in FreeBSD. Hope you > can help us to find the bug of our code. Any suggesion, comments, is > appreciated. > > For details of how the code is implemented, how our experiment is > conducted, you may need to spend one or two hours to browse through > our paper, and the source code. How is this different from the recently integrated SCTP? Best, George
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?m21wncv66z.wl%gnn>