02-14-2019 12:43 AM
Hi,
I have an Rx power high warning message in my router.
can I leave my router running with this message as it's just a warning or should I install an attenuator because in the long run the router will be damaged?
I use multimode fiber and SFP
Regards,
Solved! Go to Solution.
02-14-2019 01:33 AM
The underlying problem should be addressed. or it will eventually cause the SFP to fail prematurely.
In my experience however that's a very unusual situation for a multimode fiber connection. Usually the transmit power isn't such that it will over-run a receiver.
Can you share the output of "show interface transceiver detail" for the affected interface?
02-19-2019 11:07 PM
Ah OK, that's more normal to see with singlemode.
From the output, you are in the "warning" and not "alarm" range so it is relatively safe to continue operating like that. If it were my network and that was an important link , I'd put a 5 dB optical attenuator inline.
If you're US-based.,m you can pick one up via Amazon for US$5.99.
https://www.amazon.com/Fiber-Attenuator-Singlemode-Simplex-Fixed/dp/B001B1HOOM
02-14-2019 01:33 AM
The underlying problem should be addressed. or it will eventually cause the SFP to fail prematurely.
In my experience however that's a very unusual situation for a multimode fiber connection. Usually the transmit power isn't such that it will over-run a receiver.
Can you share the output of "show interface transceiver detail" for the affected interface?
02-19-2019 09:22 PM
i was wrong, I use a monomode SFP and fiber
mA: milliamperes, dBm: decibels (milliwatts), NA or N/A: not applicable.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
A2D readouts (if they differ), are reported in parentheses.
The threshold values are calibrated.
High Alarm High Warn Low Warn Low Alarm
Temperature Threshold Threshold Threshold Threshold
Port (Celsius) (Celsius) (Celsius) (Celsius) (Celsius)
--------- ------------------ ---------- --------- --------- ---------
Gi1/0/25 27.3 89.0 85.0 -5.0 -9.0
High Alarm High Warn Low Warn Low Alarm
Voltage Threshold Threshold Threshold Threshold
Port (Volts) (Volts) (Volts) (Volts) (Volts)
--------- --------------- ---------- --------- --------- ---------
Gi1/0/25 3.29 3.60 3.50 3.10 3.00
Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Gi1/0/25 -5.6 1.0 -3.0 -9.5 -13.5
Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
------- ----------------- ---------- --------- --------- ---------
Gi1/0/25 -0.2 + 1.0 -3.0 -19.0 -23.0
02-19-2019 11:07 PM
Ah OK, that's more normal to see with singlemode.
From the output, you are in the "warning" and not "alarm" range so it is relatively safe to continue operating like that. If it were my network and that was an important link , I'd put a 5 dB optical attenuator inline.
If you're US-based.,m you can pick one up via Amazon for US$5.99.
https://www.amazon.com/Fiber-Attenuator-Singlemode-Simplex-Fixed/dp/B001B1HOOM
02-14-2019 03:39 AM
02-24-2019 08:41 PM
I use an 1000BaseLX GLC-LH-SMD SFP with 2 meters of fiber
02-26-2019 05:37 AM - edited 02-26-2019 05:41 AM
2 meters is often quoted as a minimum, but I'm unable to find real confirmation via standards.
If you can obtain an attenuator, for $6 dollars, I would seriously consider Marvin's suggestion to install one. That would seem an inexpensive way to get your power level within spec.
02-27-2019 03:00 AM
it's ok
thanks everybody
05-01-2019 05:58 PM
this isn't an issue on low powered optics. What kind of SPF? What's the fiber cable length?
02-13-2020 08:57 AM
I have seen this on 10G SR SFPs facing a 40G QSFP Break out on a short run Multimode, and ended up buying 3 db MM attenutators surprisingly.
07-31-2022 07:43 PM
I got the high alarms issue on the 10Gbase-SR, that is connecting to the FPGA.... Somehow the port was disconnected unexpectedly....
# sh int e1/12 transceiver details
Ethernet1/12
transceiver is present
type is 10Gbase-SR
name is CISCO-AVAGO
part number is SFBR-709SMZ-CS1
revision is G4.1
serial number is AVD24179015
nominal bitrate is 10300 MBit/sec
Link length supported for 50/125um OM2 fiber is 82 m
Link length supported for 62.5/125um fiber is 26 m
Link length supported for 50/125um OM3 fiber is 300 m
cisco id is 3
cisco extended id number is 4
cisco part number is 10-2415-03
cisco product id is SFP-10G-SR
cisco vendor id is V03
SFP Detail Diagnostics Information (internal calibration)
----------------------------------------------------------------------------
Current Alarms Warnings
Measurement High Low High Low
----------------------------------------------------------------------------
Temperature 45.40 C 75.00 C -5.00 C 70.00 C 0.00 C
Voltage 3.22 V 3.63 V 2.97 V 3.46 V 3.13 V
Current 8.15 mA 10.50 mA 2.50 mA 10.50 mA 2.50 mA
Tx Power -2.51 dBm 1.69 dBm -11.30 dBm -1.30 dBm -7.30 dBm
Rx Power -0.60 dBm + 1.99 dBm -13.97 dBm -1.00 dBm -9.91 dBm
Transmit Fault Count = 0
----------------------------------------------------------------------------
Note: ++ high-alarm; + high-warning; -- low-alarm; - low-warning
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