Optics and Hardware Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

Alarm threshold configuration

Updated: June 16, 2026

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Introduces alarm threshold configuration and outlines the main concept, process, task, principle, and reference areas in this section. Guides technical users to quickly locate the procedures and supporting data they need.

Alarm threshold configuration covers alarm threshold parameters, plus FEC alarm threshold definitions, restrictions, examples, and configuration steps.

Configure alarm thresholds

Use this task to configure alarm thresholds on optics controllers.

Alarm thresholds can be configured for monitoring alarms on optics controllers.

Table 1. Alarm threshold parameters for optics controllers
Alarm threshold parameters	Description
CD	Sets the CD (chromatic dispersion) alarm threshold (cd-low-threshold and cd-high-threshold).
DGD	Sets the DGD (differential group delay) alarm threshold.
LBC	Sets the LBC (laser bias current) threshold in mA.
OSNR	Sets the OSNR (optical signal-to-noise ratio) alarm threshold.

Before you begin

Identify the optics controller and the alarm threshold parameters that you want to configure.

Procedure

Configure the CD alarm thresholds on the optics controller.

Example:

Router#config
Router(config)#controller optics 0/2/0/16
Router(config-Optics)#cd-low-threshold -2000
Router(config-Optics)#cd-high-threshold 2000
Router(config-Optics)#commit

Verify the running configuration on the optics controller.

Example:

Router#show run controller optics 0/2/0/16
Thu May 13 20:18:55.957 UTC
controller Optics0/2/0/16
 cd-low-threshold 2000
 cd-high-threshold 2000
!

Verify the configured alarm threshold values on the optics controller.

Example:

Router#show controller optics 0/2/0/16
Fri May 28 01:04:33.604 UTC
 Controller State: Up
 Transport Admin State: In Service
 Laser State: Off
 LED State: Off
 FEC State: FEC ENABLED
 Optics Status
         Optics Type:  QSFPDD 400G ZRP
         DWDM carrier Info: C BAND, MSA ITU Channel=61, Frequency=193.10THz,
         Wavelength=1552.524nm
         Alarm Status:
         -------------
         Detected Alarms: None
         LOS/LOL/Fault Status:
         Alarm Statistics:
         -------------
         HIGH-RX-PWR = 0            LOW-RX-PWR = 0
         HIGH-TX-PWR = 0            LOW-TX-PWR = 0
         HIGH-LBC = 0               HIGH-DGD = 0
         OOR-CD = 0                 OSNR = 0
         WVL-OOL = 0                MEA  = 0
         IMPROPER-REM = 0
         TX-POWER-PROV-MISMATCH = 0
         Laser Bias Current = 0.0 mA
         Actual TX Power = -40.00 dBm
         RX Power = -40.00 dBm
         RX Signal Power = -40.00 dBm
         Frequency Offset = 0 MHz
         Laser Temperature = 0.00 Celsius
         Laser Age = 0 %
         DAC Rate = 1x1.25
         Performance Monitoring: Enable
         THRESHOLD VALUES
         ----------------
         Parameter                 High Alarm  Low Alarm  High Warning  Low Warning
         ------------------------  ----------  ---------  ------------  -----------
         Rx Power Threshold(dBm)         13.0      -24.0          10.0        -22.0
         Tx Power Threshold(dBm)          0.0      -16.0          -2.0        -14.0
         LBC Threshold(mA)               0.00       0.00          0.00         0.00
         Temp. Threshold(celsius)       80.00      -5.00         75.00         0.00
         Voltage Threshold(volt)         3.46       3.13          3.43         3.16
         LBC High Threshold = 98 %
         Configured Tx Power = -10.00 dBm
         Configured CD High Threshold = -5000 ps/nm
         Configured CD lower Threshold = -5000 ps/nm
         Configured OSNR lower Threshold = 9.00 dB
         Configured DGD Higher Threshold = 80.00 ps
         Baud Rate =  60.1385459900 GBd
         Modulation Type: 16QAM
         Chromatic Dispersion 0 ps/nm
         Configured CD-MIN -26000 ps/nm  CD-MAX 26000 ps/nm
         Second Order Polarization Mode Dispersion = 0.00 ps^2
         Optical Signal to Noise Ratio = 0.00 dB
         Polarization Dependent Loss = 0.00 dB
         Polarization Change Rate = 0.00 rad/s
         Differential Group Delay = 0.00 ps
         Temperature = 21.00 Celsius
         Voltage = 3.42 V
 Transceiver Vendor Details
         Form Factor            : QSFP-DD
         Optics type            : QSFPDD 400G ZRP
         Name                   : CISCO-ACACIA
         OUI Number             : 7c.b2.5c
         Part Number            : DP04QSDD-E30-19E
         Rev Number             : 10
         Serial Number          : ACA244900GN
         PID                    : QDD-400G-ZRP-S
         VID                    : ES03
         Firmware Version       : 161.06
         Date Code(yy/mm/dd)    : 20/12/08
!

Alarm thresholds are configured, and the optics controller output shows the configured threshold values.

What to do next

Continue monitoring alarm status and alarm statistics during normal operation.

FEC alarm thresholds

Forward Error Correction (FEC) is used to control errors during data transmission. FEC works by adding data redundancy to the transmitted message. This redundancy allows the receiver to detect and correct a limited number of errors occurring anywhere in the message, instead of the transmitter resending the entire message. For additional information on FEC, see Understanding FEC and Its Implementation.

There are two types of FEC alarms:

FEC Detected Degrade (FDD) alarm: The FDD alarm is raised when the link degradation is within the permissible limit and does not cause traffic disruption. This alarm indicates the system is working harder than usual to maintain data transmission. Link degradation could be due to issues in the cable, network congestion, or other hardware failure.
FEC Excessive Degrade (FED) alarm: The FED alarm is raised when the link degradation exceeds beyond the permissible limit and causes traffic disruption. This alarm indicates the system is working harder than usual to maintain data transmission. Without corrective measures, network performance deteriorates further and eventually results in traffic loss. Link degradation could be due to issues in the cable, network congestion, or other hardware failure.

The FEC alarms threshold values can now be configured to control alarms (raise and clear FEC alarms) on both media and host side of the optical tranceiver. The optical transceiver is divided into two sides, the host side, which is positioned towards the router, and the media side, which is positioned towards the wire or cable media.

When the average bit error rate (BER) exceeds the raise threshold value , the FEC alarm is raised (or asserted). Similarly, when the BER drops below the clear threshold value , then the alarm is cleared (or de-asserted).

Table 2. Feature History Table
Feature Name	Release Information	Description
Configurable FDD and FED Alarm Threshold Values	Release 25.4.1	Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only) This feature is supported on: 8011-32Y8L2H2FH 8011-12G12X4Y-A/D
Configurable FDD and FED Alarm Threshold Values	Release 25.1.1	Introduced in this release on: Fixed Systems (8700 [ASIC: K100], 8010 [ASIC: A100])(select variants only) This feature is supported on: 8712-MOD-M 8011-4G24Y4H-I
Configurable FDD and FED Alarm Threshold Values	Release 24.4.1	Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100])(select variants only); Modular Systems (8800 [LC ASIC: P100])(select variants only) *This feature is now supported on: 8212-48FH-M 8711-32FH-M 88-LC1-12TH24FH-E 88-LC1-36EH+A8:B12 88-LC1-52Y8H-EM
Configurable FDD and FED Alarm Threshold Values	Release 24.1.1	We now ensure that you have accurate data to initiate proactive maintenance for non-critical FEC errors or take prompt action to prevent potential optical link data loss in your network. This is made possible because we've enabled the configuration of FEC (Forward Error Correction) Detected Degrade (FDD) alarm threshold values for non-critical FEC errors and FEC Excessive Degrade (FED) alarm threshold values for critical FEC errors. You can configure or clear these values for QDD-400G-ZR, QDD-400G-ZRP, and DP04QSDD-HE0 optical modules. Prior to this release, the router would automatically generate FEC alarms based on default threshold values. The feature introduces these changes: CLI: Modified the controller optics command by adding these keywords: host fec-threshold excess-degrade raise media fec-threshold excess-degrade raise host fec-threshold excess-degrade clear media fec-threshold excess-degrade clear host fec-threshold detected-degrade raise media fec-threshold detected-degrade raise host fec-threshold detected-degrade clear media fec-threshold detected-degrade clear The fec-thresholds keyword is added to the show controller optics command. YANG Data Model: New XPaths for `Cisco-IOS-XR-controller-optics-oper.yang` `Cisco-IOS-XR-um-cont-optics-fec-threshold-cfg.yang`

Guidelines and restrictions for FEC alarm thresholds

The raise threshold value must always be greater than the clear threshold value for both FDD and FED alarms.
The raise or clear threshold value of FED alarm must always be greater than the raise or clear threshold value of the FDD alarm.

While the router configuration permits a range of 1 to 18446744073709551615, the router only supports a range of 1 to 2046000000000000000. The threshold value provided by users is converted from a 64 bit number to a 16 bit number. As a result, there is minor variation between the user provided value (configured value) and the programmed value. The user input (threshold value) is appended with exponents relative to E-18.

Table 3.
Configured Value	Programmed Value (Displayed using the Show CLI command)	Pattern
1, 2, 3, ….,10	0, 1, 2,….,9	1<ConfiguredValue< 10, show command value = ConfiguredValue - 1	1->>>0.9999, displayed as 0 and so on
11,12,13,….,99	1.0, 1.1, 1.2,…9.8	10<ConfiguredValue<99, show command value = ConfiguredValue - 0.1
111,222,333…999	1.10, 2.21, 3.32	100<ConfiguredValue<999, show command value = ConfiguredValue - 0.01
1111,1112,1113 upto 2047	1.110, 1.111, 1.112…	1000<ConfiguredValue< 2047 show command value = ConfiguredValue - 0.001
2050, 12345, 23456,65432,…	2.0500, 1.2300, 2.3400,6.5400…	2047<ConfiguredValue<maximum- range show command value = first 3 digits appended by 0s

FEC alarm threshold configuration examples

Examples to configure FEC alarm threshold:

Configure FDD alarm thresholds

Use this task to set FDD clear and raise alarm thresholds on an optics controller.

FDD alarm thresholds use the host FEC detected-degrade threshold settings on the optics controller.

Before you begin

Identify the optics controller and the FDD clear and raise threshold values that you want to configure.

Procedure

SUMMARY STEPS

Configure the host FEC detected-degrade clear and raise thresholds on the optics controller.
Verify the running configuration on the optics controller.
Verify the FDD alarm threshold values on the optics controller.

DETAILED STEPS

Configure the host FEC detected-degrade clear and raise thresholds on the optics controller.

Example:

Router#config
Router(config)#controller optics 0/0/0/10
Router(config-Optics)#host fec-threshold detected-degrade clear 12000
Router(config-Optics)#host fec-threshold detected-degrade raise 22000
Router(config-Optics)#commit
Router(config-Optics)#end

Verify the running configuration on the optics controller.

Example:

Router#show running-config controller optics 0/0/0/10
Sat Feb  3 06:01:56.354 UTC
controller Optics0/0/0/10
host fec-threshold detected-degrade raise 22000
host fec-threshold detected-degrade clear 12000
!
!

Verify the FDD alarm threshold values on the optics controller.

Check the Host FEC detected degrade row in the command output.

Example:

Router#show controller optics 0/0/0/10 fec-thresholds 
FEC Threshold Information

                                 Raise                    Clear                   
 Media FEC excess degrade   :   1.2600E-02               1.2100E-02              
 Media FEC detected degrade :   1.1700E-02               1.1300E-02              
 Host FEC excess degrade    :   2.4000E-02               2.4000E-03              
 Host FEC detected degrade  :   2.2000E-14               1.1989E-14

FDD alarm thresholds are configured, and the optics controller output shows the host FEC detected-degrade values.

What to do next

Continue monitoring FEC threshold output and alarm status during normal operation.

Configure FED alarm thresholds

Use this task to set FED raise and clear alarm thresholds on an optics controller.

FED alarm thresholds use the host FEC excess-degrade threshold settings on the optics controller.

Before you begin

Identify the optics controller and the FED raise and clear threshold values that you want to configure.

Procedure

SUMMARY STEPS

Configure the host FEC excess-degrade clear and raise thresholds on the optics controller.
Verify the running configuration on the optics controller.
Verify the FED alarm threshold values on the optics controller.

DETAILED STEPS

Configure the host FEC excess-degrade clear and raise thresholds on the optics controller.

Example:

Router#config
Router(config)#controller optics 0/0/0/12                   
Router(config-Optics)#host fec-threshold excess-degrade clear 14000
Router(config-Optics)#host fec-threshold excess-degrade raise 24000
Router(config-Optics)#commit
Router(config-Optics)#end

Verify the running configuration on the optics controller.

Example:

Router#show running-config controller optics 0/0/0/12
Sat Feb  3 06:02:00.153 UTC
controller Optics0/0/0/12
host fec-threshold excess-degrade raise 24000
host fec-threshold excess-degrade clear 14000
!

Verify the FED alarm threshold values on the optics controller.

Check the Host FEC excess degrade row in the command output.

Example:

Router#show controller optics 0/0/0/12 fec-thresholds 
FEC Threshold Information
 
                                Raise                    Clear                   
 Media FEC excess degrade   :   1.2600E-02               1.2100E-02              
 Media FEC detected degrade :   1.1700E-02               1.1300E-02              
 Host FEC excess degrade    :   2.3900E-14               1.3999E-14              
 Host FEC detected degrade  :   9.0000E-03               9.0000E-04

FED alarm thresholds are configured, and the optics controller output shows the host FEC excess-degrade values.

What to do next

Continue monitoring FEC threshold output and alarm status during normal operation.

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