North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Bandwidth issues in the Sprint network
On Thu, Apr 17, 2008 at 1:00 PM, Brian Raaen <[email protected]> wrote: > Some people wanted to know what I found the problem to be. I have discovered. > the problem for a fact is the TCP window size on uploads. I have a Linux box > that I changed the Window sizes to match and I still get 32k on a upload > window and 64k on a download window. With a ping time of 50ms I have a max > theoretical throughput of 5.2Mbps Which is about what I was getting. The > formula to calculate this is the following. > > (((Ts/Tw)*Rtd)/1000)+((Ts*8)/(Lr*1000))) > > Where the following are > > Ts = Transfer size in Bytes > Tw = Tcp Window size in Bytes > Rtd = Round trip Delay in milliseconds > Lr = Line rate in bps > > At this point I am still trying to locate the offending device that is > changing the window size. After I determine for sure whether the problem is > with my router, the sprint network, or another upstream system I will let > everybody know what I find. > > > -- > Brian Raaen > Network Engineer > [email protected] > > > > > On Monday 07 April 2008, Brian Raaen wrote: > > I am currently having problems get upload bandwidth on a Sprint circuit. I > am > > using a full OC3 circuit. I am doing fine on downloading data, but > uploading > > data I can only get about 5Mbps with ftp or a speedtest. I have tested > > against multiple networks and this has stayed the same. Monitoring Cacti > > graphs and the router I do get about 30Mbps total traffic outbound, but > > individual (flows/ip?) test always seem limited. I would like to know if > > anyone else sees anything similar, or where I can get help. The assistance > I > > have gotten from Sprint up to this point is that they find no problems. Due > > to the consistency of 5Mbps I am suspecting rate limiting, but wanted to > know > > if I was overlooking something else. > > > > -- > > Brian Raaen > > Network Engineer > > [email protected] > > > Thanks for reporting back to curious minds. Mike Gonnason
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