Brocade SFP monitoring --wrong values

Troubleshooting
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1

CEE 2.2.0p35

Hi guys.

Anyone aware of this? check the discrepancies.

Brocade FC switch. Port + Check_mk value + “sfpshow” value.

16 → Rx: -2.80 dBm, → -2.8 dBm
17 → Rx: -2.70 dBm, → -2.7 dBm
18 → Rx: -3.20 dBm, → -3.2 dBm
19 → Rx: -2.80 dBm, → -2.8 dBm
20 → Rx: -2.70 dBm, → -17.0 dBm
21 → Rx: -5.60 dBm, → -2.8 dBm
22 → Rx: -2.20 dBm, → -5.6 dBm
23 → Rx: -1.50 dBm, → -2.2 dBm
24 → Rx: -2.50 dBm, → -1.5 dBm
25 → Rx: -3.20 dBm, → -2.5 dBm
26 → Rx: -2.80 dBm, → -3.3 dBm
27 → Rx: -1.90 dBm, → -2.8 dBm
28 → Rx: -2.30 dBm, → -1.9 dBm
29 → Rx: -2.50 dBm, → -2.3 dBm
30 → Rx: -2.60 dBm, → -2.5 dBm
31 → Rx: -2.70 dBm, → -2.6 dBm
32 → Rx: -2.30 dBm, → -2.7 dBm
33 → Rx: -2.20 dBm, → -2.3 dBm
34 → Rx: -1.90 dBm, → -2.2 dBm
35 → Rx: -2.00 dBm, → -1.9 dBm
36 → Rx: -2.20 dBm, → -2.0 dBm
37 → Rx: -40.00 dBm, → -2.3 dBm

Any idea? something to do with the way of monitoring?

If you want me to choose one, port 21 for example. Whom should i trust?

Thanks!!

2

Ok…

If you look closely at the mappings from Port 21 downwards, Check_mk is reporting the Rx power of Port N+1 under the label of Port N.

Shit :slight_smile:

Problem with SNMP ifIndex vs. Physical Ports

Anyone knows if there is a ongoing fix?

3

The problem here is the numbering inside your device.
This needs to be consistent. It looks more like that the -17 bBm port is not connected and also not reported inside SNMP data. If then the device continues with the numbers without a gap you have no chance to know on the SNMP side if the numbering is correct.

Here you can only inspect the SNMP data of these ports if there is something beside the “ifIndex” that can be used as unique identifier and then mapped to the real port index.
I would think this is a hard task. But it depends on the data sent.

4

Hi @andreas-doehler, thanks for your answer. All that you said is correct.

Well, we are on 2026, you know. Huge huge revolution, more than the industrial revolution. I’m talking about llm’s.

I located the .py script, corrected the code (make it work with “problematic” ports, which anyone can have… ) with the help of AI’s and that was it. Is working beautifully :).

Have a good one!