P300 SpeedFlex test , is it accurate?

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  • Updated 11 months ago
Using a P300 bridge about a quarter of a mile apart to connect a ZoneDirector 1106 to six 7782 APs. We were expecting at least 500Mbps up to 900Mbps throughput from the P300 bridge but are only getting about 200Mbps or less using Speed Flex.
Any ideas why so slow?
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Robert Wrenn

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Posted 12 months ago

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John D, AlphaDog

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SpeedFlex unfortunately is a pretty accurate and even optimistic estimate of the maximum TCP (and UDP respectively) throughputs you can expect to see across the link.

I'm not sure that 900mbits of throughput is what I would expect.... The P300 is 2x2:2 802.11ac, so even with 80MHz channels, the max PHY rate is 867mbit/s, but actual data rate will be lower due to wifi signaling overhead as well as IP overhead, noise, and signal degradation.

But that's not to say that 200 or less is what you should expect, though. Just pointing out, the intrinsic physical limits of 802.11ac 2-stream wifi makes 900mbit not reasonable. I would say around 500-600mbit is the highest rate you would expect to see in Speedflex with a pair of P300's in the most ideal of signal conditions.
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Robert Lowe

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I would be surprised to see a 2nd spacial stream hit on a P-P bridge even at 1/4 mile. What channel width are you using? Presuming you have a properly aligned link and have adequate clearance of obstacles through the link?
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Robert Wrenn

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Channel with is 40. Signal is RSSl 48 and pure line of sight with no obstacles.
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Robert Wrenn

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I see you mention 80 MHZ width Channel. We were told to use 40. Is that our problem?
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John D, AlphaDog

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80MHz channels will nearly double the max throughout and I find in practice it does close to double observed throughout. With point to point bridges I would not expect much co channel interference concerns around operating 80MHz.
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Robert Wrenn

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I am going to suggest we try the 80Mhz channel width. Will let you know what happens.
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Alan Rothenstreich

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I am having a similar issue with a pair of P300's and currently have an open case to troubleshoot why I am not seeing the expected speeds with an 80Mhz channel.  Duplicated on my bench so shall reply if we find a root cause.