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

Split-Step Fourier simulation

Updated: March 9, 2026

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Overview

Limitations of SSF simulation
How SSF simulation works
Set SSF server details
Lookup tables
Manage amplifier gains using look up table

Overview

Describes the functionality of split-Step Fourier simulation. Explains the benefits of this feature and how it contributes to efficient and robust network planning.

A split-step Fourier (SSF) simulation is a computational method that

calculates optical parameters such as OSNR and BER,
improves simulation accuracy in complex optical network scenarios, and
leverages GPU-based computation for intensive analysis.

SSF simulation is introduced alongside the e-GN algorithm to enhance the analysis of NCS 1010 networks, providing improved accuracy for optical signal-to-noise ratio (OSNR) and bit error rate (BER) simulations.

Limitations of SSF simulation

Table 1. Feature History
Feature Name	Release Information	Feature Description
Split-Step Fourier (SSF) Simulation Method	Cisco ONP Release 25.1.1	The Split-Step Fourier (SSF) method is introduced to calculate optical parameters in addition to the existing e-GN algorithm for analyzing NCS 1010 networks. This enhancement: Improves the accuracy of the simulations for OSNR and BER, particularly in complex network scenarios. Provides an SSF engine that leverages GPUs to work on intense calculations. Requests simulation generation from GENE (Generic Engine for NCS 1000 platforms) Monitors analysis progress on the GPU server, and updates the user through analysis notifications. Sends simulation results to GENE for report generation after analysis completion. Provides a Lookup Table that contains the default optical specification values for each supported amplifier. The new properties that enable the SSF method for network analysis are. At network level, Advanced Optical Settings > SSF Simulation—Enables the SSF simulation. Enable the Enable Special Settings check box to view the SSF Simulation check box At network level, Advanced Optical Settings > LUT version—Shows the default LUT version to be used for network analysis. Enable the Enable Special Settings check box to view the LUT version check box Preferences > General Settings > SSF Server Details—Allows to configure the GPU server used for SSF simulation. Manage > Lookup Table—Allows you to refer the default optical specification of the supported amplifiers.
NCS 1010 network design enhancements	Cisco ONP Release 26.1.1	Cisco ONP has implemented the following enhancements for network design: ALC Phase II Device Parameters: NETCONF XML files now include additional ALC phase II parameters, such as Raman amplification and advanced optical settings for more precise device configuration. Lookup Table (LUT) Improvements: Raman gain values are now visible in LUT entries. LUTs can be imported/exported, including CPZ data. Raman side amplification is calculated from LUT entries for better modeling accuracy. Tx connector loss is user-configurable and factored into PSD values. SSF simulation enhancements: Uses secure HTTPS protocol for communication with SSF server. Supports parallel SSF analysis from different servers when multiple users trigger the process Enables background analysis without interrupting other tasks. Displays estimated simulation timing in the analysis progress bar. These updates enhance the accuracy, configurability, security, and usability of optical network planning and simulation for NCS 1010 networks.

From Release 26.1.1, the SSF analysis includes the following enhancements:

The SSF analysis can now be executed in the background. To enable this feature, set the property "conp.backgroundAnalysis.enable" to true in the filename.properties in the location /opt/cnp/conf folder in Cisco ONP server. Once enabled, you can click the "Run in Background" button when starting the SSF analysis.
The analysis progress bar now displays the estimated remaining time for the analysis.
The SSF simulation supports the analysis of networks with multiple point-to-point disjoint networks and uses the HTTPS Protocol for communication with GPU-based SSF instances.
If multiple users configure different SSF servers on the CONP server and initiate the analysis, multiple SSF analysis can run concurrently in the background. However, if a single user starts two SSF analysis, the second analysis will remain in the queue until the first one is completed. A message stating "waiting for current SSF analysis to be completed" will be displayed in the analysis progress bar.

SSF simulation currently has these limitations:

Supports only point-to-point networks
Works only with CIM8 interfaces
Supports only colorless add/drop
Computation intensive than e-GN algorithm for better OSNR margins

How SSF simulation works

SSF simulation uses the split-step Fourier method to analyze optical parameters in NCS 1010 networks by utilizing GPU acceleration and integrating with the GENE engine.

Summary

The key components involved in the process are:

SSF engine: Runs on GPUs to perform intensive optical calculations.
GENE (Generic Engine for NCS 1000 platforms): Initiates and receives simulation jobs and results.
GPU server: Handles the computational workload and notifies you about analysis progress.
Lookup Table (LUT): Stores default optical specification values for each supported amplifier.

Workflow

The process involves these stages:

The SSF engine requests simulation generation from GENE.
The GPU server executes intensive optical parameter calculations using the SSF method.
The system monitors analysis progress and sends you notifications.
When the analysis is complete, you can view the simulation results in GENE for report generation.
The system references the Lookup Table for default optical specification values as part of the analysis.

Result

SSF simulation gives you accurate OSNR and BER simulations, especially for complex optical network scenarios, with improved computational performance through GPU acceleration.

Set SSF server details

Use this procedure to set the SSF server to run the SSF analysis.

Before you begin

Install the SSF component. See Install Cisco ONP.

Procedure

Navigate to SSF Server Details.

Choose Preferences > General Settings
In the dialog box, select SSF Server Details.

Enter the SSF server details.

SSF Server IP: Enter the server IP address.
API Key: This field is disabled.
Proxy IP: Enter the customized proxy IP address.
Proxy Port: Enter the proxy port of the server.

Click OK.

To reset the server details or close the dialog box, click Reset or Cancel.

Lookup tables

A lookup table is a configuration data structure that

stores predefined values used by analysis and simulation processes,
allows efficient retrieval of data without the need for recalculation, and
supports versioning, enabling different simulation or network scenarios.

Cisco ONP uses lookup tables (LUTs) for analysis with SSF simulation and when SSF simulation is not active. Only NCS 1010 networks use LUT values. You can enable LUT functionality only after selecting the Advanced Special Settings check box at the network level.

This table explains the range of span loss for different fiber types. LUT calculations work only if the loss stays within these ranges.


Fiber Type	Raman	Min Span loss (dB)	Max Span loss (dB)
SMF	No	5	26.5
SMF	Yes	18	33.0
E-LEAF	No	5	22.9
E-LEAF	Yes	18	32.9
TW-C	No	5	20.3
TW-C	Yes	16	30

Manage amplifier gains using look up table

Use this procedure to refer or to manage the amplifier gains in the look up table.

Procedure

Open look up table.

Choose Manage > Lookup Table

The Manage Lookup Table dialog box opens displaying the list of supported amplifiers.

Options	Actions
Search	Allows you to type in the amplifier to filter the desired lookup table.
Check boxes	Selects all amplifier tables or only the required amplifier tables.
Page numbers	Turns to the desired page.
Import	Imports the customized tables.
Export	Exports the selected tables.
Delete	Deletes the selected tables.
Cancel	Closes the dialog box.

When expanded, the table displays the optical specifications.

Table 2. Amplifier optical specifications
Parameter	Description
Fiber Type	Displays the list of supported fibers for the amplifier.
Total Loss (dB)	Displays total signal loss in dB.
SD Range	Displays the SD gain range.
Raman Amplified	Displays the status of Raman amplification in the amplifier. You can select and filter the table based on Raman gain value and whether Raman is applicable or not.
Ramna Gain	Displays the Raman amplifier gain. You can select and filter the table based on the Raman gain value.
BST PSD (dBm)	Displays the PSD value for the booster amplifier in dBm. Raman gain is used in the calculation of the PSD.
More Parameters	Contains an information button to check for additional values.

(Optional) Customize the optical specifications in the Lookup table.

Select the required amplifier.
Click Export.

The amplifier value downloads in spreadsheet.
Edit the values in the downloaded spreadsheet and click Import.

The new values are added to the Lookup table.

(Optional) Delete the customized specifications in the Lookup table.

Select the required amplifier.
Click Delete.

You cannot delete the default tables.

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