See if you can find a nother connector that can help with using iperf. Also, make sure any system testing systems have tuned IP stacks. That info is also linked from the iperf web page. http://dast.nlanr.net/Projects/Iperf/ http://www.psc.edu/networking/projects/tcptune/ Robert D. Scott Robert@ufl.edu Senior Network Engineer 352-273-0113 Phone CNS - Network Services 352-392-2061 CNS Receptionist University of Florida 352-392-9440 FAX Florida Lambda Rail 352-294-3571 FLR NOC Gainesville, FL 32611 -----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Scott Weeks Sent: Monday, April 07, 2008 5:24 PM To: nanog@merit.edu Subject: Re: Bandwidth issues in the Sprint network --- braaen@zcorum.com 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. ------------------------------------ I would not use one FTP session to test bandwidth. The rate limiting may be in the FTP software or other area of the computer. Likewise, Speedtest servers (in my opinion) are more marketing tools than testing tools. Try several similarly configured (but separate boxes) FTP servers simultaneously. If you see it go up by a factor of three you've found the issue. I have had to push my four OC-12s to Sprint to the max at times and get full BW. That's in Hawaii, but I imagine it's the same as other areas. scott