Configuration Guide for Cisco Optical Site Manager, IOS XR Release 26.x.x

PSM card protection mechanism

Updated: November 2, 2026

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This section explains pSM card protection mechanism, including key behavior and operational context that help you understand when to use the feature in Cisco Optical Site Manager.

PSM card protection switching is a high-availability mechanism that automatically transfers optical traffic from a primary Protection Switching Module (PSM) card to a redundant standby PSM card in the event of a failure or degradation of the active card.

It provides automatic failover, ensuring continuous operation and minimizing service interruption.
It enhances the overall reliability and uptime of the optical transport network.
It is typically implemented in one-plus-one or one-to-one protection schemes to maintain optical signal integrity.

Types of Protection Switching

The PSM card supports the following types of protection switching:

Revertive Protection Switching: Traffic automatically returns to the working path from the protection path once the fiber issue is resolved and the Loss of Signal (LOS) alarm is cleared on the working path.
Non-Revertive Protection Switching: Once traffic is switched to the protection path due to a signal failure, it remains on the protection path even after the failure on the working path is resolved.

Enable the revertive protection switching

Protection switching offers a safeguard against optical fiber faults. When a failure is detected, the system automatically switches live traffic from the working path to the protection path. This process ensures uninterrupted data transmission.

Revertive switching is one of the two protection switching modes. In non-revertive mode, traffic remains on the protection path even after the working path is restored. The revertive mode includes a configurable Wait to Restore (WTR) timer that delays the switch back to the working path to ensure stability.

Before you begin

Follow these steps to enable revertive protection switching on the PSM card:

Procedure

Click the Maintenance tab.
Click the Protection section to expand it.
Click the Edit button.

The fields in the table become editable.
Select true from the drop-down list under the Revertive column.
Specify the time in seconds under the Wait to Restore column.

Wait to Restore (WTR) is the time delay (in seconds) applied after a Loss of Signal (LOS) alarm on the working path is cleared. Once the WTR timer expires, traffic is switched back to the working path.
Click Apply.

Revertive protection switching is enabled on the card.

Revertive protection switching automatically switches traffic back to the working path after the fault is cleared and the WTR timer expires. This process minimizes service disruption and optimizes network performance.

What to do next

Configure the non-revertive protection switching

Non-revertive protection switching ensures that, once traffic is switched to the protection path due to a signal failure, it remains there even after the failure on the working path is cleared.

Non-revertive switching contrasts with revertive switching, where traffic automatically returns to the working path after fault resolution. Non-revertive mode is often used to maintain traffic on the protection path until a manual switch is performed or other conditions are met. It is also applicable in MPLS-TE path protection and EVPN configurations to control failover behavior.

Before you begin

Follow these steps to enable or disable non-revertive protection switching on a PSM card interface:

Procedure

Click the Maintenance tab.
Click the Protection section to expand it.
Select the check-box corresponding to the PSM switch and then click Protection Switch button.

The New Switch Command dialog box is displayed.
Complete these steps to enable non-revertive switching in the New Switch Command dialog box:
1. Select the interface you want to lockout from the Target Interface drop-down list.
2. Select Lock-Out from the Switch Command drop-down list.
3. Click Apply.
Complete these steps to disable non-revertive switching:
1. Select Release from the Switch Command drop-down list.
2. Click Apply.

Traffic remains on the protection path after a failure is cleared. This behavior avoids potential disruptions that can result from switching paths repeatedly. When non-revertive mode is disabled, traffic reverts automatically to the original working path once it is restored.

Perform a manual switch

A manual switch lets you transfer traffic between the working and protection paths. Typically, this switch is used during scheduled maintenance or when manual intervention is necessary.

Before you begin

Follow these steps to perform a manual switch:

Procedure

Click the Maintenance tab.
Click the Protection section to expand it.
Select the check-box corresponding to the PSM switch and then click Protection Switch button.

The New Switch Command dialog box is displayed.
Select the interface you want to manually switch to from the Target Interface drop-down list.
Select Manual-Switch from the Switch Command drop-down list.
Click Apply.

The system status shows the manual switch state and confirms that the traffic is switched.

ONS-QSFP-PSM2 pluggables

A COSM capability for ONS-QSFP-PSM2 pluggables is a feature set that

represents a pluggable protection switching module (PSM) as a pluggable port module (PPM) and an associated protection group,
enables flexible provisioning and management of working and protection interfaces, and
allows centralized monitoring and management of multiple protection groups within a single card view.

After COSM creates the pluggable port module (PPM), you manage the PSM protection groups using familiar procedures for protection-switching, alarm handling, and performance monitoring. The ONS-QSFP-PSM2 is also visible in the NFV view.

Table 1. Feature history
Feature Name	Release	Feature
Support for ONS-QSFP-PSM2 pluggable on NCS 1014	Cisco IOS XR Release 26.3.1	Cisco Optical Site Manager supports the ONS-QSFP-PSM2 pluggable on NCS 1014 ports in channel protection mode. Users can provision interfaces and protection groups, perform protection switching, monitor performance and threshold-crossing alerts, and review alarms through the Cisco Optical Site Manager GUI or NETCONF. This unified workflow reduces operational effort and simplifies protection management. The PSM pluggable supports these line cards: NCS1K4-QXP-K9 NCS1K14-2.4T-K9 NCS1K14-2.4T-X-K9

ONS-QSFP-PSM2 management in COSM

Open the PPM from the rack view or card view to manage the selected pluggable. The PPM view provides access to the existing PSM management functions.

ONS-QSFP-PSM2 configuration considerations

Configure the baud rate to match the protected channel when you use signal-power switching. A matching value improves power measurement accuracy and switching time.
Revertive switching and automatic threshold calculation do not operate together. Enable only one of these functions.
When automatic threshold calculation is enabled, it controls the receive low thresholds for the working and protected paths. Use manually configured receive low thresholds only when automatic threshold calculation is disabled.
Safety control mode is intended for path protection. In Release 26.3.1, the configuration is available but is not fully qualified for channel protection.

Provision an ONS-QSFP-PSM2 pluggable on a supported NCS 1014 port

Enable PSM operating mode for a port equipped with an ONS-QSFP-PSM2 pluggable to activate protection and management capabilities.

Use this task to provision a supported NCS 1014 line-card port in PSM mode and access advanced protection and management options for the pluggable through COSM.

Before you begin

Ensure the ONS-QSFP-PSM2 pluggable is installed on a supported NCS 1014 line-card port.
Add the NCS 1014 device to COSM and verify that the device is reachable.
Ensure that your COSM account has device-configuration privileges.

Follow these steps to provision an ONS-QSFP-PSM2 pluggable in PSM mode:

Procedure

Click the Topology tab.

The topology view displays the managed NCS 1014 device.
Right-click the line card that contains the pluggable and choose Open Card.

The card view displays the line-card ports and installed equipment.
Click the Provisioning tab.

The Provisioning tab displays the configurable card resources.
Expand the Pluggable Port Modules section.

The table displays the Port, PPM Type, OLS Mode, Admin State, Service State, and Actual Equipment Type columns.
Click the Edit button.

The editable fields and the Apply action become available.
From the OLS Mode list for the target port, choose psm.

The target row displays psm as the selected OLS mode and identifies the actual equipment as ONS-QSFP-PSM2.
Click the Apply button.

COSM accepts the configuration and refreshes the PPM table.
Right-click the configured port and choose Open PPM.

The ONS-QSFP-PSM2 PPM view opens and displays the management tabs.

The selected port operates in PSM mode, and COSM displays the ONS-QSFP-PSM2 PPM view for management and monitoring.

What to do next

Use the existing PSM procedures to configure the protection group, operate a protection switch, or monitor the pluggable.

ONS-QSFP-PSM2 representation

These tables outline the key identification attributes, COSM interface views, and optical interfaces for the ONS-QSFP-PSM2 pluggable module.

Table 2. ONS-QSFP-PSM2 identification in COSM
COSM item	ONS-QSFP-PSM2 representation
Actual Equipment	ONS-QSFP-PSM2
PPM Type	QDD-PSM-PPM
OLS Mode	psm
Protection group	One protection group for each provisioned ONS-QSFP-PSM2 pluggable. The group refers to the working and protection interfaces of that pluggable.
Card view	Displays each installed ONS-QSFP-PSM2 PPM. A card can contain more than one pluggable PSM and protection group.
NFV view	Displays the ONS-QSFP-PSM2 and its common, working, and protection interfaces.

Table 3. ONS-QSFP-PSM2 optical interfaces
Path	Interfaces	Purpose
Common	COM-RX and COM-TX	Connect the protected signal to the PSM.
Working	W-RX and W-TX	Represent the normal traffic path.
Protection	P-RX and P-TX	Represent the alternate traffic path.

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