Cisco Optical Network Controller Configuration Guide, Releases 26.x.x

OTN circuits

Updated: September 15, 2026

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Explains OTN circuit discovery and monitoring in Cisco Optical Network Controller, including protected and unprotected circuits, service discovery, link utilization, service history, and detailed service paths.

An OTN circuit is a logical transport connection that

uses pre-existing GMPLS OCH trails that are created on an NCS2K-400G-XP-LC card in OTN-XC card mode,
appears in Service Manager, topology views, and the Circuit Monitoring workspace, and
supports protected circuits with a standby protection path and unprotected circuits with a single active path.

OTN circuit discovery scope

Cisco Optical Network Controller supports brownfield discovery of OTN circuits that are already provisioned on the network using CTC or other tools.

Automatic discovery of OTN services in Service Manager on the OTN tab
Circuit Monitoring workspace with active route, protection status, and alarm visibility
OTN link utilization summary with export to Excel option
Service event history with event type classification and export to Excel option
Service detailed path

OTN circuit types and topology representation

An OTN circuit is a logical transport connection that

carries client traffic over an OTN layer that runs on GMPLS OCH trails,
is discovered and displayed by Cisco Optical Network Controller as a protected or unprotected circuit, and
shows the active working path, protection standby path, underlying OCH trail, and OTS physical route.

OTN topology layers and circuit path visualization

Cisco Optical Network Controller provides two topology layers for OTN visibility:

OTN layer: Shows OTN circuits and their paths between endpoint transponder nodes. Inline amplifier sites (OLA/ILA) that are not terminated at the OTN level are not displayed in this layer.
OTS layer: Shows the full physical route including all nodes, links, and inline sites. OTN circuits are not directly highlighted in this layer.

The visual representation of OTN circuit paths in the circuit monitoring workspace uses these conventions:

Solid line: The active working path of a protected circuit, or the active path of an unprotected circuit
Dotted line: The standby protection path of a protected circuit

When a protection switch occurs, the topology highlight updates to reflect the new active route. The highlight always shows the currently active route, not the configured working route.

Note

In release 26.1.1, ILA (Inline Line Amplifier) and OLA (Optical Line Amplifier) inline sites that are not terminated at the OTN layer are not shown in the OTN topology map. To view the full physical route including inline sites, navigate to the underlying OCH trail and switch to the OTS layer.

This table compares OTN and OTS topology layer visibility.

Table 1. OTN versus OTS topology layer comparison
Attribute	OTN layer	OTS layer
OTN circuit path highlighted	Yes	No
Inline sites (OLA/ILA) visible	No	Yes
OCH trail visible	No	Yes
Protection status shown	Yes	No

Discover OTN services for NCS2K-400G-XP-LC card in Service Manager

Discover OTN services for an NCS2K-400G-XP-LC line card in Service Manager.

In release 26.1.1, OTN services are supported in the OTN-XC card mode of the NCS2K-400G-XP-LC line card. Use this procedure to discover OTN services for the NCS2K-400G-XP-LC line card.

Note

Use this procedure if you have not created an OCH-Trail GMPLS circuit for the NCS2K-400G-XP-LC line card in CTC.

Follow these steps to discover OTN services for an NCS2K-400G-XP-LC line card:

Procedure

Configure the OTN-XC card mode on trunk ports 11 and 12 in the NCS2K-400G-XP-LC line card.

In the Nodes screen, click the IP address of the node and provision the OTN-XC card mode in Cisco Optical Site Manager.
Create an OCH-Trail GMPLS circuit in Cisco Optical Network Controller or CTC.

OTN services for the NCS2K-400G-XP-LC line card are visible in the OTN tab.

Monitor OTN circuits

Monitor OTN circuits to verify circuit health, active path routing, protection status, and any alarms affecting the circuit.

The circuit monitoring workspace provides a unified view of OTN circuits, including topology visualization, detailed service, and service history panels. The workspace displays both protected and unprotected circuits discovered from the network. You can navigate between the OTN layer and the OTS layer to correlate circuit path information with the physical network topology.

Before you begin

OTN circuits are provisioned using CTC or other tools and discovered and displayed in Cisco Optical Network Controller on the OTN tab in Service Manager.

Follow these steps to monitor OTN circuits:

Procedure

Open the Circuit Monitoring workspace.

Go to Workspaces > Circuit Monitoring > Launch.

The circuit monitoring workspace appears displaying trails and OTN circuits in the topology panel. Trails are shown in the OTN layer and serve as the underlying transport on which OTN circuits are built.
Click the OTN toggle button in the topology to display OTN circuits.

The OTN topology shows the OTN links and circuits between endpoint nodes. You can switch between the OTS and OTN layers using the layer selector buttons in the topology panel.
Select an OTN circuit to open the detailed service panel.
For a protected circuit, the circuit detailed service panel shows:
- Active working path (solid line on topology)
- Standby protection path (dotted line on topology)
- Protection status for each path segment
- Link status pop-up when hovering over path segments
The circuit detail panel opens, showing path information, protection status, and any active alarms for the selected circuit.
Right-click a node or card in the Cisco Optical Network Controller topology and choose View in Nodal UI to open the component in Cisco Optical Site Manager.

Cisco Optical Network Controller opens the Cisco Optical Site Manager interface at the specific card location. From Cisco Optical Site Manager, you can perform maintenance operations such as protection switching. Direct protection switching from the Cisco Optical Network Controller web UI is not available in Release 26.1.1.
Right-click a node or card in the Cisco Optical Network Controller topology and choose View PM History (port) to view performance monitoring graphs for a specific port.
Clicking the port link redirects to the interface PM view. Clicking directly on a port row in the PM view opens the historical PM graph for that interface. The PM view supports range filters (for example, 3 hours) to control the time window displayed in the graph.

These PM data types are available on trunk ports:
- Optical channel PM (200G trunk only)
- OTU PM (trunk interfaces)
- ODU PM (all ODU containers)

The circuit monitoring workspace displays the selected OTN circuit with its active route highlighted in the topology and circuit details shown in the detail panel.

Monitor OTN link utilization

Monitor OTN link utilization to assess bandwidth consumption and capacity across the OTN links in your network.

The link utilization view in Cisco Optical Network Controller displays current bandwidth usage for all OTN links associated with a circuit. Utilization is expressed as a percentage of total link capacity.

If a port has no allocated circuit (no cross-connect installed), its bandwidth row is not populated in the OTN link utilization table. When a circuit is added, the row appears and utilization updates accordingly.

Note

At least one OTN circuit must be discovered and visible.

Follow these steps to monitor OTN link utilization:

Procedure

Open the link utilization view in the OTN link monitoring workspace or Links app.

For Link Monitoring workspace: Go to Workspaces > Link Monitoring > Launch.

The Link Monitoring workspace displays all OMS links. Go to the OTN Links tab.

For Links app: In the left panel, click Links.

The Links app opens and displays the OMS tab. Go to the OTN tab.
In the Span Utilization column, click View summary.

Span utilization summary for an OTN circuit appears displaying ODU ports and their parameters.

ODU Utilization is shown as a percentage. For example, two 10G containers on a 200G link produce a 10% utilization figure.

Figure 1. Complete span utilization summary
Review the utilization percentage for each OTN link.
The table displays these parameters for each link:
- ODU port number
- Bandwidth allocated
- Service name
- Utilization percentage
Unused ports or bandwidth that has no allocated circuit are shown with an empty bandwidth value.

You can view the current OTN link utilization percentages and export the data to Excel using Excel for offline analysis or reporting.

View OTN service event history

View the OTN service event history for a selected OTN circuit.

The service history for an OTN circuit displays a table of events associated with that circuit. Events are classified by event type, such as success or info. In Release 26.1.1, success events are generated only for initial discovery events, when the OTN service is first created. Protection switch events and state changes are reported as info events. The event table supports column resizing and export to Excel.

Note

The View more link is shown only when additional event details are available.

Follow these steps to view OTN service event history:

Procedure

In the circuit monitoring workspace, select an OTN circuit from the circuit list.

The circuit detailed service list panel opens, showing topology, path information, and available tabs including service history.
Click the Service History tab to view the event log for the selected circuit.
The event table displays these columns:
- Timestamp: The date and time of the event (displayed in UTC)
- Event name: A description of the event, such as protection state change or successful discovery
- Event type: Classifies the event as success, info, or neutral
- More details: A link to additional event details, if available
You can resize columns by dragging the column header borders.
The service event history table loads, showing all events recorded for the selected OTN circuit.
(Optional) Click the Export icon in the service history toolbar to export the event history.

The event history is exported to an Excel file containing all event records currently visible in the table.

You can review the complete event history for the selected OTN circuit and export the log to Excel for offline analysis or audit purposes.

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