North American Network Operators Group
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Re: Bandwidth issues in the Sprint network

  • From: Sam Stickland
  • Date: Tue Apr 08 12:57:30 2008

Could be your TCP window size? A 17520 byte TCP window (Windows 2000) will cause a single flow to top out at 5Mbps at about 50ms. What is the latency on the link?

Try some figures here and see what limit you might be hitting:

http://www.wand.net.nz/~perry/max_download.php?bits_per_second=155000000&ack_size=40&no_delayed_acks=2&mss=1460&rtt=35&wsize=17520&ploss=0

Sam

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.