Can't rely on the noise level reading indicated on a live link's status screen. (although we tend to put a lot of weight on the noise shown using the Spectrum Scanner over a period of time, paying attention to the peak value (blue line) ). But even then, the results are shown as a single reading, and not individually for each polarity. What happens if one polarity is low noise and the other polarity has super high noise?
For a noise free 2 mile ubiquiti link at 20Mhz, dual pol, we can actually get Iperf to push 70mbps. Although testing with devices/laptops attached tp ends of the radios. So if you can only get 40mbps, something is wrong with the testing method or the link. Heck, a 10mhz channel can push 35-40mbps with Iperf, at top modulation.. You could continue further by dropping down to 10Mhz, and seeing the rate of change. Also at 20Mhz, you have the flexibilty to change channels to make sure you aren't centered on a bad channel. What speed does the UBNT embedded speed test show? Note UBNT test is also based on TCP. On average our testing usally will see very simlar speed results comparing the UBNT built in test to Iperf. If UBNT test is also slow, you definately have a link issue. If UBNT test is much faster, then scrutinze your testing devices. Or play with Iperf to make sure its not the Iperf setting s you are using requiring tweaking. Also, if using Iperf, try parallel streams, to see if you get a higher agregate throughput. That will tell you if it is a real capacity limit, or a TCP slow down issue due to quality. It should be noted that the UBNT Rocket using it's embeeded test tool, can successfully perform a full speed test. I've tested up to 85mbps. So, to reduce variables, to trouble shoot a link problem, rely on the embedded test tool until such time that the embeeded tool can reach full speed. Once that is accomplished, you can scrutinize link quality further with Iperf. The only need for Iperf is to test multi-hop to a non-UBNT end point, or parallel streams, to gather more data. We had an issue with Bullets not to long ago, where 5.3.3 firmware was super slow, but switching down to a 5.2 version solve the performance problem. But that is not a Rocket. We've used later firmwares for Rockets fine, usually. When you push traffic does your modulation change frequently? or stay steady? Generally its good practice to leave radio set to a max mode equivllent to what it will stay at on average without downshifting. if your link generally stays steady on a mode/modulation, and you are not getting throughput appropriate for that modulation, using the UBNT inbedded tests, its usually a timing thing, preventing the link from functioning optimally. Manually stting the ACK time is one thing that is within your control to play with. When in doubt, if nothing makes sense, and you cant solve it, try changing firmware. Not only upgrade but downgrade. This has fixed our performance issues numerous times, even though a clear answer of why, was not determined. What antennas are you using? Are they UBNT? If not, do they have a high enough port-to-port isolation? You also cant rule out multipath self interference, as with that you wont see noise if you aren't transmitting. You can try narrowing antenna beamwidth, if you aren't already. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: Patrick D. Nix, Jr To: WISPA General List Sent: Monday, October 24, 2011 5:52 PM Subject: Re: [WISPA] UBNT Rocket M5 Throughput Ok tried 20mhz, throughput drops about 10mbps to about 30mbps. My signal is at least 20db better than noise (signal -59 noise -85+). ACK is set auto with distance of 2 miles (actual distance is approx 1.5mi). cable not an issue. any thoughts? From: [email protected] [mailto:[email protected]] On Behalf Of Tom DeReggi Sent: Monday, October 24, 2011 3:27 PM To: WISPA General List Subject: Re: [WISPA] UBNT Rocket M5 Throughput You probably either have 1) noisy channels, 2) incorrect ACK distances, 3) not optimal firmware version, 4) Or some third party factor effecting testing, such as testing devices that cant generate that much traffic or buffer sizes of routers. The first thing to try is switch down to 20mhz channel and see if the speed tests stays the same or higher, or if it drops proportionally. I bet the 20Mhz channel will perform better. Dont rely on CCQ on its own. Its one indicator, but does not mean you have a clean channel for sure. Also remember, the Eth port is limited to 100mb, and if there is cable quality issues such as due to distance, it could autoadjust to half duplex. Test laptop to PC, isolating RF path, just for grins. It is very rare to find 40Mhz of clean spectrum for Dual polarity, and even the slightest packet loss and delay can drastically reduce TCP throughput. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: Patrick D. Nix, Jr To: WISPA General List Sent: Monday, October 24, 2011 3:50 PM Subject: Re: [WISPA] UBNT Rocket M5 Throughput Problem is when I turn airmax on the speed really goes in the toilet. Best I can get is about 20mbps. According to ubiquiti airmax needs to be off up to 15km links, anything over that airmax needs to be on. Do you have good success with short airmax ptp links? From: [email protected] [mailto:[email protected]] On Behalf Of Travis Johnson Sent: Monday, October 24, 2011 2:45 PM To: WISPA General List Subject: Re: [WISPA] UBNT Rocket M5 Throughput Turn AirMax on. Travis On 10/24/2011 1:36 PM, Patrick D. Nix, Jr wrote: What is the best real TCP throughput up/down anyone is getting on a PtP ubnt connection? We have two rocket M5 approx 1.5 mi, CCQ 97-98%, 40mhz channel width, airmax off. Displayed TX/RX rate is 270/270. Real TCP throughput via iperf radio to radio is 40-45mbps. Are there some config changes needed perhaps? --------------------------------------------------------------------------------WISPA Wants You! 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