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Guru Elite

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Wolfie99,

 

There are quite a few factors that go into figuring it out.  If you have time, the Outdoor Mimo Networks VRD here:  http://www.arubanetworks.com/wp-content/uploads/OMWN_VRD_2012-01-04-1.pdf goes into great detail about that.  I would just end up copying and pasting that information here.

 


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Occasional Contributor II

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Thanks Joseph,

 

I'll go through that document in details.

Highlighted
MVP Expert

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Wolfie,

 

Are you using two wireless clients on each side of the 175 bridge to do your thorughput tests or are you doing wired tests? If you are testing wireless client-to-client iperf, then your numbers are about right (your two wireless clients are half-duplex hitting nearly half of the theorietical max). You will/should see much higher thorughput when you wire in both clients (one on each side). You also should be testing large frames and multiple streams. What iperf strings are you using to do your test?

 

In short, in case you are doing wireless client, change to makeing both sides wired, 4-stream tests with larger packets sizes. Also UDP tests will be faster than TCP. 

 

@400m with those antennas, you should be able to get well over 100Mbps unless your 5Ghz air is not clean. The outdoor VRD has a rate versus range graph to give you a good idea.


Jerrod Howard
Distinguished Technologist, TME
Occasional Contributor II

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi Howard,

 

Thanks for the reply. Yes.. I'm having one laptop each on both sides of the mesh portal and point. Each laptop is connected wired to the data port of the mid-span injector where the MPP and MP are connected.

 

So when I run iperf test between the 2 clients, the mesh link is my transport medium. It looks like this :

 

 

switch ----- iperf client (wired) --> ====================== <-- iperf server (wired) --- switch

                                                             (mesh link 300/300 Mbps)

 

 

The iperf parameters we used at both sides are as follows :

 

Iperf –c 1.2.3.4   -w 512k  -t 60   -P 4

Iperf –s  -w 512k

 

 

I can achieve an UL / DL speed of 300/300 Mbps for the mesh link and a RSSI value of 38dbm. Theoretically, I should be able to achieve a throughput close to 150Mbps right? But I'm only getting around 77Mbps throughput. Is this acceptable?

 

 

Thanks

 

Highlighted
MVP Expert

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Sorry, a previous post you had mentioned something about the client's wireless NICs.

 

So your RSSI is good, great even, and your iPerf looks fine to me. The next question would be if there is any other RF in the area using the same channel, adjacent APs on the same channel, etc? If you change your mesh link's channel (say 161- or 153+, etc), do you still see the same speeds and channel utilization?

 

Your power injectors, are they Gig rated at 802.3at, and the mid-span's links are for sure running at gig speeds? 



Jerrod Howard
Distinguished Technologist, TME
Highlighted
Occasional Contributor II

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi Howard,

 

Thanks for the prompt response. Really appreciate it. I did not check the port speed of the mid-span injector. I'll need to verify it. You have a point there :)

 

As for the surrounding, I did checked using InSSIDer and there're no other APs in the same channels. Anyway, the external antennas are mounted high on the rooftop so co-channel interference is pretty minimal.

 

Due to country restriction, we are able to use only channel 149+ and 157+. So the 2 pairs of mesh portal-point are using bonded-channels which are far apart.

 

Thanks

 

Highlighted
MVP Expert

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Just as an FYI, if there is another mesh link/bridge setup, InSSIDer would not show the bridge link, just something to be aware of in case there is another 5Ghz bridge setup. Your antennas are 60deg wide, which means they can pick up a large swath of neighboring RF.

 

You have two mesh bridges setup, are they both IAP-175s and do both bridges show the same uplink speeds across the mesh? You may want to open a TAC case and get them all the tech information for them to review. Usually it's an issue with interference when both sides are showing good RSSI and bandwidth. But TAC can work out the details and/or steer you to other possibilities.

 

Good luck, let us know what you find or what TAC steers your way. 


Jerrod Howard
Distinguished Technologist, TME
Highlighted
Occasional Contributor II

Re: Poor RSSI and throughput between 2 IAP-175 mesh

Hi Howard,

Yes. They are both AP175 and both mesh links are showing a good 270/300 link speed across. I'll open a TAC case on this.

 Will keep you posted on the outcome.

 

 

Thanks for the advice.