We have seen this on every 5GHz "Lite" AP we have installed. We have
RMA'd all of them to date that we didn't wait too long to deal with. The
problem was clear upon initial installation, it did not occur over time.
We have never seen it on a non-"Lite" model. We just don't buy them
anymore, especially since now we are onto 450i.
Matt Hopkins
Network Administrator
[email protected]
onlinenw.com <http://onlinenw.com>
On 8/31/2016 4:24 PM, George Skorup wrote:
Yes. I have a handful of APs that show all SM uplink SSRs imbalanced.
All 3.65, IIRC. Downlink SSR is fine. Uplink rates still run MIMO-B.
Maybe it's a calibration issue on those APs. And yes, I have noticed
it since the day they were installed. We haven't bothered to replace
them. And I just haven't had time to dig into it.
I'll just say that even though an SM's session may show 8.0dB B-A,
SNRs look normal (35B, 35A for example). That's on the AP session
page, power tab. And yes, that's with the SM actively passing traffic.
Is it a real problem or cosmetic, perhaps due to a calibration issue?
I don't have a clue.
On 8/31/2016 4:12 PM, Darren Shea wrote:
Has anyone else had an issue with Cambium PMP450 APs where one of the
polarities starts to get weaker - it's hard to detect until someone
has an
issue, but it usually manifests for us as a sudden, drastic change in
the
Signal Strength Ratio (V-H) on the AP, for all connected SMs.
Normally, it's
pretty close to zero, as long as there is traffic, but when the problem
manifests, the typical value will shoot up to anywhere from 8 to 20dB
(absolute value, since sometimes it's the Vertical Polarity, other times
it's the Horizontal). I built an MRTG tracking page for this value
for a few
LUIDs on each AP, and it has brought the problem to our attention for
some
APs, but we only catch it when we are looking, and the fact the
values are
unpredictable if no traffic is flowing makes this a difficult graph to
read..
Here's the thing - we've had six APs with this issue. We take them
down and
replace just the AP (same sector antenna, it doesn't get moved, same
antenna
leads, etc.), and it always fixes the problem. We have also done
bench tests
on the troubled APs, taking care to keep every single thing about the
test
precisely the same, other than the AP, and we can duplicate the same
failure
mode - it follows the AP, and the AP alone. Unfortunately, even though
there's a common failure mode, these didn't all have the decency to fail
during their first year of service, and we haven't had any luck
getting them
repaired, either. Are we seeing something unique, or has this
happened to
anyone else?
Just wondering
-- Darren
