Cisco NCS 1010 Optical Applications Configuration Guide, IOS XR Release 25.x.x

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Events leading to band failure

Updated: February 5, 2026

Overview

This topic lists the typical events that can result in band failure for optical communication systems and provides an example scenario showing system output following an L-band failure.

Band failure can occur due to several events, such as connectivity issues, device failures, and power loss.

Events leading to band failure

Band failure can happen due to any of these events:

  • Optical connectivity fails between devices operating in the C-band and L-band.

  • The amplifier or controller on the L-band or C-band device has failed.

  • The amplifier on the L-band or C-band is shut down due to Optical Safety Remote Interlock (OSRI).

  • The node is shut down due to power failure.

  • Line cards operating in the L-band or C-band are in a cold-reload state.

  • A card operating in the L-band or C-band fails.

  • Multiple fiber cuts and high availability events.

  • High back reflection.

Note

Span fiber failure is not considered as band failure as both bands are impacted due to the failure.

Example of L-band failure

This scenario illustrates the BFR procedure in the event of an L-band failure. As soon as the band failure is detected, BFR sets safe mode on the failed band devices and switches the PSD profile of the surviving band devices to single-band PSD. The status of the devices operating in the C band is ACTIVE and the PSD profile for the devices is displayed as Single Band.

Figure 1. Example of L-band failure
Example of L-band failure

This example shows the status of BFR when the L-band is in the FAILED state. In this case, all the C-band nodes are switched to single-band PSD profiles and L-band devices are set to the safe mode.


RP/0/RP0/CPU0#show olc band-status
Controller              : Ots0/0/0/0
Self-Band               : C-Band
BFR status              : Running
Node RID                : 10.2.1.1

Self IP Address         : 192.0.2.1
Self Controller         : Ots0/0/0/0
Partner IP address      : 192.0.2.2
Partner Controller      : Ots0/0/0/0
Partner link status     : UP
C-Band status           : ACTIVE
C-Band PSD              : Single Band        
L-Band status           : FAILED
L-Band PSD              : NA
Node RID                : 10.2.1.2
 
Self IP Address         : 192.0.2.21
Self Controller         : Ots0/0/0/0
Partner IP address      : 192.0.2.22
Partner Controller      : Ots0/0/0/2
Partner link status     : UP
C-Band status           : ACTIVE
C-Band PSD              : Single Band
L-Band status           : FAILED
L-Band PSD              : NA
Node RID                : 10.2.1.3

Self IP Address         : 192.0.2.31
Self Controller         : Ots0/0/0/0
Partner IP address      : 192.0.2.32
Partner Controller      : Ots0/0/0/2
Partner link status     : UP
C-Band status           : ACTIVE
C-Band PSD              : Single Band
L-Band status           : FAILED
L-Band PSD              : NA
Node RID                : 10.2.1.4
Self IP Address     : 192.0.2.41
Self Controller         : Ots0/0/0/0
Partner IP address      : 192.0.2.42
Partner Controller      : Ots0/0/0/0
Partner link status     : UP
C-Band status           : ACTIVE
C-Band PSD              : Single Band
L-Band status           : FAILED
L-Band PSD              : NA
Node RID                : 10.2.1.5
Self IP Address     : 192.0.2.51
Self Controller         : Ots0/0/0/0
Partner IP address      : 192.0.2.52
Partner Controller      : Ots0/0/0/0
Partner link status     : UP
C-Band status           : ACTIVE
L-Band status           : FAILED
L-Band PSD              : NA