4506E: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -18.4 dBm.

[mannygawadcco]

Hi Folks,

I am currently setting up a new data center with 2 4500E switches as core running VSS, however i am having threshold violation indication power low alarm. Please note that the violation is showing even if there is no fiber patch cord connected to any of the interfaces, both switches are showing the same error message.

Below are the system and log info for more details! Kindly provide me with the working solution for the issue.

Cisco IOS Software, IOS-XE Software, Catalyst 4500 L3 Switch Software (cat4500es8-UNIVERSAL-M), Version 03.06.03.E RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Wed 26-Aug-15 21:49 by prod_rel_team

Cisco IOS-XE software, Copyright (c) 2005-2015 by cisco Systems, Inc.
All rights reserved. Certain components of Cisco IOS-XE software are
licensed under the GNU General Public License ("GPL") Version 2.0. The
software code licensed under GPL Version 2.0 is free software that comes
with ABSOLUTELY NO WARRANTY. You can redistribute and/or modify such
GPL code under the terms of GPL Version 2.0.
(http://www.gnu.org/licenses/gpl-2.0.html) For more details, see the
documentation or "License Notice" file accompanying the IOS-XE software,
or the applicable URL provided on the flyer accompanying the IOS-XE
software.

ROM: 15.1(1r)SG4
CORESW uptime is 6 days, 22 hours, 31 minutes
Uptime for this control processor is 26 minutes
System returned to ROM by SSO Switchover
System restarted at 02:40:56 UTC Sun Aug 26 2018
Running default software
Jawa Revision 3, RadTrooper Revision 0x0.0x41, Conan Revision 0x1449

Last reload reason: Reload command

License Information for 'WS-X45-SUP8-E'
License Level: entservices Type: Permanent
Next reboot license Level: entservices

cisco WS-C4506-E (P5040) processor (revision 2) with 4194304K bytes of physical memory.
Processor board ID FXS1821Q1PH
P5040 CPU at 2.2GHz, Supervisor 8-E
Last reset from Reload
7 Virtual Ethernet interfaces
144 Gigabit Ethernet interfaces
28 Ten Gigabit Ethernet interfaces
511K bytes of non-volatile configuration memory.

Configuration register is 0x2101

%SFF8472-5-THRESHOLD_VIOLATION: Te1/4/1: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -18.4 dBm.
%SFF8472-5-THRESHOLD_VIOLATION: Te1/4/2: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -18.4 dBm.
%SFF8472-5-THRESHOLD_VIOLATION: Te1/4/3: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -18.4 dBm.

CORESW#show int te1/4/1 transceiver
ITU Channel not available (Wavelength not available),
Transceiver is internally calibrated.
If device is externally calibrated, only calibrated values are printed.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
NA or N/A: not applicable, Tx: transmit, Rx: receive.
mA: milliamperes, dBm: decibels (milliwatts).

Optical Optical
Temperature Voltage Tx Power Rx Power
Port (Celsius) (Volts) (dBm) (dBm)
--------- ----------- ------- -------- --------
Te1/4/1 29.8 3.23 -1.2 -40.0

I hope that any can provide me with the viable solutions.

Thank you very much in advance!

-manny

[Leo Laohoo]

Try shut/no shut the ports.

[mannygawadcco]

Hi I got the same issue!

[Marvin Rhoads]

When a transceiver is live on an interface (and not in shutdown state) it will trigger the alarm when:

a. there's nothing plugged into it. or

b whatever is plugged in isn't providing signal that of the proper type that also exceeds the low power threshold. -40.0 dBm is the noise floor of a transceiver so if something is plugged into it the other end either isn't transmitting, the polarity is reversed, an intermediate patch isn't plugged in properly / tight on one side etc. (a few of the most common causes).

[mannygawadcco]

Thanks Marvin, 

I will try those steps and let you know, but prior to that i have connect the SC-SC fiber patch cord and i got the same error, both interface are having the same status "down".

[Marvin Rhoads · Accepted solution]

Steps to check:

1. confirm both of the transceivers are the same type (use "show inventory" command to check)

2. confirm the transmit power of each transceiver ("show interface transceiver detail").

3. confirm the tx/rx polarity of the connector.

[yhaifi001]

Hi Manny,

I had the same problem, pleae can you share what did you do to resolve this problem.

Thank you

[Leo Laohoo]

You're better off raising a new thread as this one is old.

[robert.lorrison]

This is normally not indicative of a problem, unless the interface in question is up. If it isn’t disabled, the tranceiver will flag itself as below the threshold simply because there isn’t fiber plugged into the port or whatever is plugged into it isn’t producing a signal (in which case, the interface would be down).

If the interface IS up, however, then the most likely culprit is faulty cable.

[ittworldwide]

Hello All,

in my case it was a WS-C3750X-48PS-S with a C3KX-NM-10G, that kept showing a very similar error, the issue was actually that one of the SFP-10G-SR transceivers were faulty. Once I replaced it, the error stopped.