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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Bandwidth issues in the Sprint network
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] > Attachment:
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