topic Re: AirMarshall RSSI values in Wireless

AirMarshall RSSI values

Raphael_L — Fri, 03 Oct 2025 18:34:40 GMT

Hi ,

I'm trying to understand the values returned by AirMarshal.

I'm seeing SSIDs near my APs with some anormal values :

I'm no wireless expert but a RSSI of 137db seems impossible.

I can find approx 100ish other SSIDs on multiple sites with those values. Has anyone ever seen that ?

Re: AirMarshall RSSI values

aleabrahao — Fri, 03 Oct 2025 18:40:34 GMT

That’s not just unusual, it’s physically impossible in the context of Wi-Fi signal strength.

RSSI is typically measured in dBm, a logarithmic unit that expresses power relative to 1 milliwatt.
In Wi-Fi, RSSI values are negative, ranging from around -30 dBm (excellent) to -90 dBm (very poor).
A value like 137 dBm would imply a signal strength far beyond any realistic or safe transmission level, it’s likely a misinterpretation or bug.

Re: AirMarshall RSSI values

Raphael_L — Fri, 03 Oct 2025 18:49:12 GMT

That's what I'm thinking but I don't think Meraki is displaying RSSI in negative. I have never seen a negative value with Airmarshal.

https://documentation.meraki.com/MR/Monitoring_and_Reporting/Location_Analytics

RSSI - 95 = signal strength in dBm

Still 137 doesn't make sense at all.

I can also find frequently values of 255. Something is off

Re: AirMarshall RSSI values

aleabrahao — Fri, 03 Oct 2025 19:18:15 GMT

I'll be honest, I don't remember why in Meraki the value is displayed in dB. 😅

Re: AirMarshall RSSI values

aleabrahao — Fri, 03 Oct 2025 19:23:50 GMT

I'm thinking here, could 137 dB represent total gain (for example, sum of antenna + amplifier gain), but not the received signal?

Re: AirMarshall RSSI values

aleabrahao — Fri, 03 Oct 2025 19:37:20 GMT

I think I found the explanation.

For example, if a client device's radio receives a signal at -75 dBm, and the noise floor is -90 dBm, then the effective SNR is 15 dB. This would then reflect as a signal strength of 15 dB for this wireless connection.

https://documentation.meraki.com/MR/Wi-Fi_Basics_and_Best_Practices/Signal-to-Noise_Ratio_(SNR)_and_Wireless_Signal_Strength

But 137db is still unrealistic.

Re: AirMarshall RSSI values

RWelch-USA — Fri, 03 Oct 2025 19:46:56 GMT

Seems odd (really really high) - curious what MR firmware are you running in your network?

And do you have RRM enabled (perhaps the AI-RRM factor is contributing in this equation - somehow)?

Asking because when I look at Air Marshall using my APs (MR 31.1.8) I too see elevated #s. The two at the bottom are both my APs in blue. And I do have AI-RRM enabled.

Re: AirMarshall RSSI values

Rasmus Hoffmann Birkelund — Sat, 04 Oct 2025 16:44:32 GMT

Without argueing whether or not something is off in AirMarshall, often people tend to confuse dB witth dBm (or dBW or any other measurement).

Decibel, or dB are generally just a measurement of ratio, or gain as @alessandrodematos also notes. When we talk about a change in 10 dB, this refers to a change in order of magnitude, while 3 dB is a change in 2's +3dB is times 2, while -3 dB is times 0.5).

When we talk about dBm, this is a measurement of change in decibels in reference to milliwatts. If the reference point it watts, it'll be dBW.

Honestly, showing neighbors or rogues seen by own Access Points with a measurement of dB, doens't really make sense to me. A measurement of 137 dB could be a lot - but it could also be insignificant. It depends on the frame of reference.

137 dBf, and no one bats an eye.

137 dBW, and you're cooked. Well done, even.

Re: AirMarshall RSSI values

Raphael_L — Mon, 06 Oct 2025 13:33:12 GMT

Did more digging this morning.

{"ssid":"DIRECT-E6-HP OfficeJet 3830","bssids":[{"bssid":"E7","contained":false,"detectedBy":[{"device":"KK","rssi":138},{"device":"AS","rssi":3},{"device":"J7","rssi":8},{"device":"TK","rssi":11}]}]

AirMarshal flags this BSSID at 130++db on a single AP. Going to RF Spectrum the RSSI ( in dbm ) is -70dbm which is low and makes more sense since the other APs are already reading this BSSID with a low value.

Tested with MR 30.7 and MR31.1.8 same results. It's always 1 AP on the lot that is showing odd values.

Also why are the values inconsistent?

AirMarshal RSSI = db RF Spectrum RSSI + Client page = dbm

Re: AirMarshall RSSI values

p.deleuw — Tue, 07 Oct 2025 10:29:46 GMT

My dashboard shows the nearest "Other SSIDs" with the lowest dB value. I think, it is not the RSSI. As other mentioned, this should be expressed as dBm and should be negative. Just take a look at Network-wide > Monitor > Clients. Choose any wireless client and click on it. You see a metrik "Signal", expressed in dB. This is, according to the documentation, the SNR. I think, the value given by Air Marshal is the SNR, too.

Re: AirMarshall RSSI values

Raphael_L — Wed, 08 Oct 2025 14:05:12 GMT

Hi Raphael

This is a known issue that is resolved in firmware version MR 31.1.6 (Stable release candidate). Please upgrade the devices and let me know if the issue still occurs.

I just wished ( real bad ) that MR firmware would include more fixes instead of "General fixes and improvement". This would prevent me from opening a ton of cases.

Will try that firmware and report