Re: Baltimore train tunnels (was Re: Vulnerbilities of Interconnection)
At 09:47 PM 9/7/2002 -0400, Sean Donelan wrote:
Unlike phone calls, TCP traffic doesn't occur in fixed bandwidth increments. TCP traffic, 90% of Internet traffic, is elastic. By design, TCP adjusts the traffic rate to keep the bottleneck congested. As the bottleneck moves, traffic reacts by increasing or decreasing the rate to match the available capacity. This feedback occurs independently of what is happening on nearby traffic paths. Even if there is available capacity on elsewhere, the current Internet design is not very good at using it. Some people view this as an inefficient use of available capacity, other people view it as a self-protective mechanism.
Thank Goodness for well-behaved applications, right? ( Misbehaving TCP stacks and UDP-based apps don't obey these back off rules. ) I remember Van Jacobson gave a presentation back in 1997 that spoke about the problems with applications that didn't exhibit these characteristics: http://www.academ.com/nanog/october1997/ It would be interesting to see some recent verification that well-behaved TCP-apps are the norm on the Internet...any data out there in this regard? Bill
Thank Goodness for well-behaved applications, right? ( Misbehaving TCP stacks and UDP-based apps don't obey these back off rules. )
It would be interesting to see some recent verification that well-behaved TCP-apps are the norm on the Internet...any data out there in this regard? You can see a clear demarkation in the UDP Vs TCP study by WPI (ftp://ftp.cs.wpi.edu/pub/techreports/pdf/02-17.pdf)..Particularly
You can see lot of intiatives to make things more TCP friendly to avoid hogging of bandwidth by some selected applications( mostly multimedia based.) More details on the intiative can be obtained from http://www.psc.edu/networking/tcp_friendly.html. Equation based congestion control and DCCP are some of the options for such applications which doesnt obey back off rules. figure 6. Also, the analysis of mice Vs elephants is important in addtion to mis-behaving flows. Also, Sally floyd maintains a page on recent measurement studies on TCP-friendly application. (http://www.icir.org/floyd/tcp_unfriendly.html) __________________________________________________ Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes http://finance.yahoo.com
participants (2)
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senthil ayyasamy
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William B. Norton