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throughput issue w/ ZF 7962

christopher_sco
New Contributor II
I just stumbled on to a weird problem that's completely baffling me... I have a ZoneDirector 1000 controller and three ZoneFlex 7962 devices. One of the ZF 7962 is exhibiting very slow throughput - given that our office's connection is 100d/20u and that the other two ZF WAPs perform as expected when running speedtest.net, this third unit shows 15d/10u and I can't figure out why.

I've performed speed tests, via the ZoneDirector, to each of the units and they max out, so it doesn't appear to be a wiring issue. Even when I join my laptop to the WAP in question and I'm literally standing ten feet away from it, my performance speeds stink.

Any troubleshooting tips/recommendations?
10 REPLIES 10

primoz_marinsek
Valued Contributor
If you used the integrated ZAP in the ZD and it shows max tp on cable WITHOUT any packet loss than it may mean that you have interference in one location.

You can maybe check the packet retry rate at the AP and post it here so we'll get a better clue.

Go to the Monitor :: APs in the ZD and look for "Histogram of PHY errors per second". If there is alot of ph errors from 2k up then that's most likely the case.

michael_brado
Esteemed Contributor II
Primoz is right, if that AP is more affected by interference in the client band than on the other two. The System Info file (click first icon to the right of AP under Monitor/
Access Points page), is a text file you can read with Notepad++. Athstats are the
radio details (radio0 = 2.4, radio1 = 5G), and the Histogram shows a 2 minute
rolling RF sample. This data appears at the bottom of the files, just before AP
syslogs.

Secondly, since most modern clients can use all 11 of the 2.4 channels, you may
wish to employ the ChannelFly algorithm to manage channel assignment, (from
the Configure/Services, Self-Healing section). Having 3+ APs is helpful, and
ChannelFly also looks at non-802.11 interference, to help select the best of all
11 available 2.4G channels. You should see optimal throughput after Channelfly
has had a little time for your APs to build their internal channel/interference tables.

Lastly, compare Speedflex from the ZD to APs/clients, as well as your othe client
speed tests. You may find good local network times, but that your Internet
connection is the slow point.

christopher_sco
New Contributor II
First off, thank you both for your input.

The Speedflex test for allthree WAPs show both up- and down-link to be 400+Mbps w/ zero packet loss.

As for the Histogram, here's what I've got:

(rafters) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 1 2 26 57 12 2 0 0 0

Compare that to my two other WAPs:

(annex) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 3 18 21 31 22 5 1 0 0

and

(mezz lng) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 3 29 45 17 2 2 1 0 0

And I don't see much of a difference...

I've turned on the ChannelFly function for both 2.4 and 5; will report back in a few days.

Thanks again...

michael_brado
Esteemed Contributor II
All three APs show higher than desired number of PHY errors. You don't want to
see over 2K/second. The first two APs report 60% of packets have 5K+ PHY errors
per second.

(rafters) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 1 2 26 57 12 2 0 0 0

Compare that to my two other WAPs:

(annex) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 3 18 21 31 22 5 1 0 0

and

(mezz lng) Histogram of PHY errors per second (pcttime in each range)
0 1-500 ..1K ..2K ..5K ..10K ..20K ..50K .100K more
0 3 29 45 17 2 2 1 0 0

These histograms indicate some possible constant EMF interference near
the APs. You don't want them too close to florescent lighting ballasts, electrical
conduits, heating/AC ducts, elevators, machinery, etc.

Have you run Channelfly on 2.4G for a little while to see if these numbers might
come down after letting the algorithm evaluate interference?
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