nanog mailing list archives
Re: Bandwidth issues in the Sprint network
From: Brian Raaen <braaen () zcorum com>
Date: Thu, 17 Apr 2008 17:00:12 -0400
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 braaen () zcorum com 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 braaen () zcorum com
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Current thread:
- Re: Bandwidth issues in the Sprint network, (continued)
- Re: Bandwidth issues in the Sprint network Brian Raaen (Apr 08)
- RE: Bandwidth issues in the Sprint network Matthew Evans (Apr 08)
- Re: Bandwidth issues in the Sprint network Sam Stickland (Apr 08)
- Re: Bandwidth issues in the Sprint network Brian Raaen (Apr 08)
- Re: Bandwidth issues in the Sprint network Mike Gonnason (Apr 09)
- RE: Bandwidth issues in the Sprint network Frank Bulk (Apr 09)
- Re: Bandwidth issues in the Sprint network Mike Gonnason (Apr 09)
- Re: Bandwidth issues in the Sprint network Michael Holstein (Apr 09)
- RE: Bandwidth issues in the Sprint network Murphy, William (Apr 09)
- Message not available
- RE: Bandwidth issues in the Sprint network Frank Bulk (Apr 10)
- Re: Bandwidth issues in the Sprint network Mike Gonnason (Apr 09)
- Re: Bandwidth issues in the Sprint network Brian Raaen (Apr 08)
- Re: Bandwidth issues in the Sprint network Mike Gonnason (Apr 17)
- RE: Bandwidth issues in the Sprint network Lincoln Dale (Apr 17)
- Re: Bandwidth issues in the Sprint network Chris Adams (Apr 17)
- RE: Bandwidth issues in the Sprint network Robert D. Scott (Apr 07)
- Iperf 2.0.4 Released Kevin Oberman (Apr 07)
- RE: Bandwidth issues in the Sprint network Frank Bulk (Apr 10)