First Published: April 29, 2020

Business Challenge of Manual Optimization of Submarine Optical Links

During field installations, the manual optimization of submarine optical links for maximum spectral efficiency is a cumbersome and time-consuming process. The process involves a manual tuning of the line cards by searching for an optimal combination of line rates, BPS, and channel spacing.

The Cisco Automated Subsea Tuning (Cisco AST) overcomes this challenge. Cisco AST is a cloud hosted microservices-based software application. Cisco AST determines the spectral efficiency of the optical links automatically by using real time data obtained from devices at both ends of the optical link.

In a system that uses Cisco NCS 1004 devices, Cisco AST automatically tunes the NCS 1004 transponder that is connected to any DWDM line system by using real-time performance information, to optimally use the subsea cable capabilities. This tuning is done during field installation of the system and also during re-optimization of the links in future.

Cisco AST collects network data and analyses, executes the tuning algorithm, and deploys the configuration in the system.

This solution is beneficial for customers who use Cisco’s optical submarine network systems. By using Cisco AST during device installations, they can maximize their link capacity, and so reduce their operational cost.

Install Cisco AST on a Centralized Server

The Cisco AST application is delivered as a bundled tar file signed by Cisco, to ensure the authenticity of the package. The tar file contains the following files and folders:

  • A shell script (ciscoAir.sh) to install on a CentOs machine

  • A docker-compose file (docker-compose.yml) referring to the images in the local repository with a version tag

  • An images folder (images) that has images of Cisco AST microservices in a tar file with the file format tar.gz.

  • A docker-installation folder (docker_installation) that has docker-ce rpms and docker-compose installation file

  • A signature file (<PkgName>.signature)

You will receive a product information document containing the signature verification key, through eDelivery, after you purchase and download the tar file.

When it is executed with the appropriate commands, the script performs installation, start, and stop processes of the application.

Before you begin

You must have the following:

  • VM with minimum 16GB RAM, eight Core CPU with CentOs v7.6, and a storage of at least 50GB

  • Docker version 19.03.2, build 6a30dfc (The install script installs this version of docker if it is not found on the VM).

  • Docker-compose version 1.24.1, build 4667896b (The install script installs this version of docker compose if it is not found on the VM).

  • Check the firewall rules on the VM or server where you install the Cisco AST, to ensure that HTTPS port 443 is open.

The following table lists the supported browser versions:

Table 1. Supported Browser Versions

Browser

Latest Version

Minimum Browser Version

Google Chrome

81.0.4044.122

72.0.3626

Mozilla Firefox

75.0

68.6.0esr version

Microsoft Edge

81.0.416.64

44.18362.449.0

Procedure

Step 1

To install the Cisco AST application, perform the following steps:

  1. Download the cisco-air-<version>.tar.gz from Cisco Commerce Workspace (CCW) tool to your VM. 

    [root@air-devm-1 package_test]# ls -l
    Total 42224144
    -rw-r—r--. 1 root root 4325523238
    [root@air-devm-1 package_test]#

  2. Extract the tar file in the installation directory.

    [root@air-devm-1 package_test]# tar -xvf cisco-air-<ver>.tar.gz
    ciscoAIR.sh
    pkgs.tar.gz

    After you extract the package, the contents of the tar file are unpacked. Verify that the unpacked contents include the signature file.

  3. Copy the key available in the information document into a file. Save the file to the installation folder on the server and run the installation script with the key filename as one of the arguments: 

    ./ciscoAir.sh -o install -t clean -m offlinemode -k <public_key_file>

    This ensures that the installation happens only if the image signature is verified.

  4. Install the application using the script available in the extracted tar file.

    [root@air-devm-1 package_test]# sudo./ciscoAIR.sh
    2020-02-12 11:58:37 Invalid arg Operation type cannot be empty Exiting
    Usage: ./ciscoAIR.sh -o <install|start|stop> -t <update|clean> -m <offlinemode>
    Usage: ./ciscoAIR.sh -o install -t clean -m offlinemode
    Usage: ./ciscoAIR.sh -o install -t update -m offlinemode
    -m offlinemode will install from included tar
    User need to enter username and password when prompted which will be used for application login
    [root@air-devm-1 package_test]#

    The installation requires several minutes, because it extracts and loads the required images required from the bundled packages tar file. 

    [root@air-devm-1 package_test]# sudo./ciscoAIR.sh -o install -t clean -m offlinemode

    • -o Install -t clean -m offlinemode―Installs the unpacked tarfile on the host machine cleaning any previously installed images.

    • -o Install -t update -m offlinemode―Installs the unpacked tarfile on the host machine without cleaning any previously installed images.

    • -o start―Starts the stopped Cisco AST services simultaneously. It requires a previous installation to run this command. If the Cisco AST services are already up, this command option execution does not perform any action.

    • -o stop―Stops Cisco AST services currently running on the host machine. 

    Starting install
    Starting installation. This could take several minutes to load the images 
    removed ‘airInstall.log’
    2020-02-12 11:59:23 Extracting tar filepkgs.tar.gz
    docker-compose.yml
    images/

    The script prompts you to provide your own web server certificate at the time of installation. You must copy this certificate in the installation location where the docker-compose file is available at the folder path certs/air-ui.

    During the installation procedure, the script prompts you to provide a user name and password. You must use this credential to log in to the Cisco AST application. 

    2020-02-12 12:19:19 Load image completed
    Please enter Username: demo-user
    Please enter Password (Min 8 chars):
    Note 

    The username must be alphanumeric, and can include hyphens and underscores. The password length must be in the range of 8–12 characters.

    If the installation is successful, the following message appears:

    2020-02-12 12:21:10 Installation Success
    [root@air-devm-1 package_test]#

    If the installation is not successful, share the log file (airInstall.log) that is generated in the installation folder with the Cisco support team to troubleshoot installation issues.

    Note 

    When you perform a clean installation again on the same VM, the script does not again prompt you for the username and password. The same username and password that you had provided earlier persists.

    After successful installation, start the application.

    Note 

    To enable the IPv6 devices to onboard Cisco AST, ensure that you check the following:

    • Verify that VM has a network interface with a valid and routable IPv6 address.

    • Execute the following command: 
      sudo ip6tables -t nat -A POSTROUTING -o <ipv6-interface-name> -j MASQUERADE
      Example: 
      sudo ip6tables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

    • Verify that Cisco AST connects to IPv6 devices.

    You can also add this command to a startup script residing at (/etc/rc.local ) to make it persistent across reboot.

Step 2

To start the Cisco AST application, enter the following command: 

[root@air-devm-1 package_test]# sudo./ciscoAIR.sh -o start
Starting start
Starting the application, will take few minutes for the application to come up
2020-02-12 12:21:10 Executing Docker-compose UP

This command starts all the relevant containers. This could take up to two minutes to start the application and bring up all the services.

Step 3

Go to https://<host-name> and login to the application.

Step 4

(Optional) To stop the Cisco AST application, enter the following command: 

[root@air-devm-1 package_test]# sudo./ciscoAIR.sh -o stop
Starting stop
2020-02-12 16:30:07 Executing Docker-compose down

Cisco AST Limitations

The following limitations apply:

  1. You must have root access to the server on which you install the Cisco AST application. The server infrastructure must be secure for uninterrupted functioning of the Cisco AST application.

  2. You can access Cisco AST application by using only the user credentials provided during the installation. Multiple users can use the same credentials to access the application simultaneously. We recommend to store the password safely because it cannot be recovered.


    Note

    The user has an admin role. User credentials must be shared with only those users who will use the Cisco AST application.

  3. When selecting the device pairs in a tuning project, ensure that you select only the physically connected ports of the near-end and far-end devices. Otherwise, the tuning results become unpredictable.

  4. Cisco AST does not perform the gRPC Remote Procedure Call server authentication because the certificates installed on the NCS1004 devices for gRPC connection may not be uniform.

  5. By default, the slot 1 is allocated for pairing the devices. Because NCS1004 has two carriers for each slot, the tuning fails if you proceed with the default number of slots. Therefore, we recommend you to select a minimum of two slots for tuning.

  6. Cisco AST generates a confirmation code after you enter the authorization code when you update the license. You must enter the confirmation code in the CSSM portal. If you do not enter the confirmation code in the CSSM portal, then the confirmation information about the updated license is not stored in the CSSM portal. When you update or remove the license in the CSSM portal, it prompts you for the confirmation code again. You can locate the confirmation code which was not captured earlier, in the Technical Support Logs for entry in the CSSM portal.

  7. Ensure that you do not stop or restart the Cisco AST services, while installing, updating, or returning the Cisco AST licenses. Otherwise, it may lead to unknown license reservation states and behavior.

Log into the Cisco AST Web Interface

Use this task to log into the Cisco AST web interface (Cisco AST instance).

Procedure

Step 1

In the browser URL field, enter the IP address or hostname where Cisco AST is installed.

The login page appears.
Step 2

Enter the username and password.

You must use the credentials that you chose during the installation. You can change the password later.
Step 3

Click Sign In.

The home page appears with the main menu in the left panel. By default, the Smart Software Licensing page is displayed.

The following table describes the task you can perform in the home page.

Table 2. Cisco AST Home Page Menu

Menu

Description

Devices

Onboard the devices to be tuned. See Onboard Devices to Cisco AST.

Projects

Create and tune a project. See Tune Devices Using Cisco AST.

Admin

View the audit logs. See Troubleshoot Cisco AST Issues Using Logs.

License

Reserve license, update reservation, and return the license. See Manage Licenses in Cisco AST Using Smart Licensing.

Login

Sign out of the application and change the password.
Step 4

(Optional) To change the password, perform the following steps:

  1. Click the icon in the bottom-left of the page and select Change Password.

    A dialog box appears.

  2. Enter the Current Password, New Password, and Confirm Password.

  3. Click Save.

Manage Licenses in Cisco AST Using Smart Licensing

Smart Licensing is a cloud-based, standardized licensing platform that simplifies and streamlines the management of your software licenses from one centralized website. For more information, see Cisco Smart Software Licensing.

Cisco AST is an offline-based licensed software application. You can use Cisco AST in evaluation mode for 90 days; this mode supports tuning of eight ports of NCS1004 devices.

Cisco AST supports only Specific License Reservation (SLR), which is an offline mode of license consumption. There are two categories of licenses.

  • Right to Use (RTU)―License to use the software.

  • Right to manage (RTM)―License to perform tuning on the ports.

You can run Cisco AST in subscription mode by purchasing and adding the following entitlements to your virtual account in Cisco Smart Software Manager (CSSM).

Table 3. License Entitlements

Entitlement

Product tag

S-OAS-AIR-LIC

OAS Automatic Inline Retuner Software RTU

S-OAS-AIR-RTM-TXP1

OAS Automatic Inline Retuner NCS 1004 1.2T TXP port RTM

In order to be compliant, you must reserve one RTU license and multiple RTM licenses for each instance of the Cisco AST installation. If you have reserved only RTM licenses, but not RTU licenses, then the product becomes noncompliant.

The reserved RTM licenses are utilized for a tuning project until tuning is in progress. When you confirm the tuning result either by selecting Accept, Reject, or Revert, the RTM licenses are automatically released back to the reserved pool of licenses for that Cisco AST instance. You can reuse the released RTM licenses for other projects.

Reserve Licenses for Cisco AST

Use this task to reserve licenses for Cisco AST.

Before you begin

Log into the Cisco AST Web Interface.

Procedure

Step 1

Click the icon in the left panel.

Step 2

Click Reserve License.

The License Reservation Request dialog box appears.

Step 3

Click Copy to Clipboard to copy the reservation code or Click Save as file to save the code to a file.

Step 4

Login to CSSM Portal using the Cisco provided username and password.
Step 5

Choose your smart account from the Virtual Account drop-down list.

Step 6

Click the License tab.

Step 7

Click License Reservation.

The system displays the Smart License Reservation wizard.

Step 8

On the Enter Request Code tab, paste the reservation request code that you have generated or upload the file where the code is saved, and click Next.

Step 9

On the Select Licenses tab, check the Reserve a specific License check box.

The system displays the list of surplus licenses available in your virtual account.

Step 10

Enter the number of licenses that you want to reserve for the RTU and RTM licenses, in the Reserve field.

You must select at least one RTU license.
Step 11

Click Next.

Step 12

On the Review and Confirm tab, click Generate Authorization Code.

The system displays the Authorization Code that is generated.
Step 13

Click Copy to Clipboard to copy the code or download it as a file.

Step 14

In the Cisco AST UI, Click Continue in the License Reservation Request dialog box.

Step 15

Click Enter Reservation Authorization Code.

Step 16

In the Enter Reservation Authorization Code dialog box, paste the authorization code, or upload the file where the authorization code is saved.

Step 17

Click Install.

After successful installation, the following message appears:

Authorized and Reserved

Update License Reservation

When you want to reserve RTM licenses to tune more ports, you can update the reserved licenses.

Procedure

Step 1

Log in to the CSSM portal using the Cisco-provided username and password.
Step 2

Click the Inventory tab.

Step 3

From the Virtual Account drop-down list, select your smart account.

Step 4

From the Product Instances tab, for the Cisco AST instance, click the Actions tab and choose Update Reserved Licenses.

Step 5

On the Select Licenses tab, check the Reserve a specific License check box, and update the number of licences.

Step 6

Click Next.

Step 7

On the Review and Confirm tab, click Generate Authorization Code.

The system displays the authorization code that is generated in the Authorization Code tab.

Step 8

Click Copy to Clipboard to copy the code or download it as a file.

Step 9

Login to Cisco AST. See Log into the Cisco AST Web Interface.

Step 10

Click the icon.

Step 11

Click Update Reservation.

Step 12

Paste the authorization code copied from the CSSM or upload the file where the code is saved.
Step 13

Click Install.

After the successful installation, the following message appears:

Authorized and Reserved

Cisco AST generates a confirmation code to be updated in the CSSM portal.

Step 14

Click Copy to Clipboard.

Step 15

Log in to the CSSM portal.
Step 16

Click the Inventory tab.

Step 17

From the Virtual Account drop-down list, choose your virtual account.

Step 18

Click the Product Instances tab.

The list of product instances available is displayed.
Step 19

Click the required Cisco AST instance to expand the same.

The Overview window is displayed.

Step 20

From the Actions drop-down list, choose Enter Confirmation Code.

The Enter Confirmation code window is displayed.

Step 21

In the Reservation Confirmation Code field, paste the confirmation code.

The confirmation code is updated on CSSM.

Return Licenses

Use this task to return the license reservation for Cisco AST.

Before you begin

Log into the Cisco AST Web Interface.

Procedure

Step 1

Click the icon in the left panel.

Step 2

Click Return License.

Step 3

Click Continue in the Return License Conformation dialog box, to confirm.

The License Reservation Return Code dialog box appears.

Step 4

Click Copy to Clipboard to copy the reservation code or click Save as file to save the code in a file.

Step 5

Log in to CSSM portal.
Step 6

Click the Inventory tab. From the Virtual Account drop-down list, select your smart account.

Step 7

In the Product Instances tab, for the Cisco AST instance, click Actions drop-down menu and choose Remove.

Step 8

When prompted, paste the return code, and click Remove product Instance.

The Registration Status becomes UNIDENTIFIED in the Cisco AST user interface and the application returns back to the evaluation mode.

Onboard Devices to Cisco AST

Cisco AST does not discover the NCS 1004 devices automatically. You must onboard the devices that need to be tuned before initiating a tuning process.

Cisco AST supports the following traffic modes.

  • Trunk Side: 200G, 250G, 300G, 350G, 400G

  • Client Side: 100GE client automatic configuration only

    OTU4 client requires a manual configuration.

Manage Devices

Use this task to add devices into the inventory and edit the device details.

Before you begin

Log into the Cisco AST Web Interface.

Procedure

Step 1

To add the devices manually for onboarding, follow these steps:

  1. Click Devices in the left panel.

  2. Click New.

  3. Enter the device details that are needed to connect to the device and perform actions, such as get Inventory, set configuration, and get operational data.

    Ensure that you enter valid a username and password of the device to enable Cisco AST to connect to the device.

  4. Click Save.

    The new device is onboarded and added to the Devices table. Cisco AST validates the connection with the onboarded device.

    The Name column includes name, image, device connection status, and an icon indicating the connection status.

    • Green―Device is connected.

    • Yellow―Device is waiting to be connected.

    • Red―Device is disconnected.

      Cisco AST does not automatically reconnect a disconnected device. Select the disconnected device and click Reconnect.

      If the device is reachable, the device gets reconnected and the status changes to connected.

  5. Repeat Steps b through d to add additional devices.
Step 2

To view the device inventory, follow these steps:

  1. Click Devices in the left panel.

  2. Select the device that you want to edit and click Edit or click the device name under the Name column.

  3. Click the Inventory tab.

    If the device is reachable, the live inventory details of the device appear.
Step 3

To change the device details of the onboarded device, follow these steps.

  1. Click Devices in the left panel.

  2. Select the device that you want to edit and click Edit or click the device name under the Name column.

  3. Modify the device details as required.

  4. Click Save and Close.

Step 4

To delete an onboarded device, follow these steps:

  1. Click Devices in the left panel.

  2. Select the device that you want to delete.

  3. Click Delete.

  4. Confirm the deletion.

    The selected device gets deleted.

    Note 

    You cannot delete a device that is part of the tuning project.

Projects

A project represents a container of the following information needed for the tuning process:

  • Devices involved in the tuning process

  • Device pairing process

  • A set of input parameters that can be adjusted to modify the tuning behavior

A project is a persistent entity. Both input parameters and tuning results are stored in the database and available for future operations.

Furthermore, the project represents a single tuning instance, and therefore parallel tuning can be performed on different project instances.

Tune Devices Using Cisco AST

The tuning workflow is an end-to-end process that starts from creating a project and ends at verifying the final configuration for deployment. The following flow diagram depicts the tuning workflow.


Warning

The tuning workflow is based on a procedure that requires the power-off of the channels along the workflow and during the final configuration. This can affect the stability of the link and impact any existing channel that shares the same spectrum.

Table 4. Tuning Workflow

Workflow Sequence

Detailed Steps
Create a Project

  1. Click Projects on the left panel.

  2. To create a new project, follow these steps:

    1. Click New.

      The New Project dialog box appears.

    2. Enter the Project Name and choose the Near-End Location and Far-End Location.

      Cisco AST filters the devices to be tuned based on the location chosen. Therefore, the devices belonging to other locations cannot be tuned.

  3. To edit a project, follow these steps:

    1. Choose the project and click Edit.

    2. Modify the required parameters in the Edit Project dialog-box.

    3. Click Save.

  4. To delete a project, use the following steps:

    1. Choose the project that you want to delete.

    2. Click Delete.

Open the Project Wizard

  1. Click Projects in the left panel.

  2. Click the name of the project that you want to tune.

The project wizard opens.
Select

Select the devices for pairing:

  1. Choose the Near-End Device and Far-End-Device from the drop-down lists.

  2. Choose the Number of Slots to be connected between the selected devices.

    The chosen number of slots is the maximum available slots for both devices in a pair.

  3. Click Add or the + icon next to the pair to add more device pairs.

  4. To delete a pair from the project, click the delete icon next to the pair.

  5. Click Continue.

Pair Pair the near-end and far-end devices.

  1. Choose the slots to be paired from the Slot drop-down lists for both the devices.

    You can also cross-connect the slots belonging to the same device pair. For example, you can choose slot 0 for the near-end device and slot 3 for the far-end device.

  2. You can exclude a pair from tuning, using the Include toggle button.

  3. Click Continue.

    The devices are paired. If the pairing is successful, a green line appears between the paired devices; otherwise, a red line appears.

Properties

Set properties for the base configuration. For more information, see Base Configuration Properties.

The default values for the properties appear.

  1. Modify the values as required.

    You can also upload the properties from a file (.csv) that is available in your system.

  2. Click Continue.

Spectrum

Specify the forbidden regions of the spectrum if necessary.

  1. Choose the Blocking Spectrum N Start Frequency, the Blocking Spectrum N Stop Frequency, and the Width of the spectrum.

  2. Click Continue.

The subsea configuration values that are derived from the properties are displayed.
Subsea

Modify the subsea configuration values if needed.

  1. Choose the pair whose subsea parameters you want to edit.

  2. Click Edit.

    The Sub-Configuration dialog box displays the default values.

  3. Modify the subsea configurations. For more information, see Subsea Configuration Parameters.

  4. Click Okay.

  5. Click Continue.

Configuration

  1. Verify the configuration values for tuning.

    Cisco AST builds the baseline configuration based on the carrier properties provided. The baseline configuration is the starting point for subsequent tuning.

  2. Click Continue and Apply if you agree with the baseline configuration, else click Back to modify the properties and the subsea configuration.

    Note 

    • While deleting a channel, ensure that you replace the spectral slot with the same noise value. Retaining the spectral range outside the bandwidth that is allocated to the project that is completely occupied prevents link instability and enables you to maintain the channel power at a constant.

    • You must manually configure the proper channel plan on the terminal equipment.

  3. Click Apply to confirm the tuning process.

If the number of licenses that are reserved is enough to tune the number of ports selected, Cisco AST proceeds with the tuning. Otherwise, you must reserve sufficient licenses and begin the tuning workflow.

The tuning process begins by applying the baseline configuration. You can view the progress of the tuning process. After the tuning process is complete, you can view the tuning results. It is a set of measurements that are performed on the tuned devices after applying the configuration.

Tune

The upper area of the Tune page displays histogram graphs and the lower area displays a table that reports configuration and status information for each interface of the tuned devices.

The histogram graphs gives a clear indication of power trends and margin distributions. Transmit power scale is displayed on the right side of the graph. Margin scale is on the left side. On the top-left corner, you have toggle buttons to switch between the variables on the horizontal and vertical axes. You can choose one of the following combinations:

  • Frequency versus SNR-Margins

  • Frequency versus Q-Margin

  • Wavelength versus SNR-Margins

  • Wavelength versus Q-Margin

Perform one of the following depending on whether you accept the tuning results:

  1. Click Reject to reject the final configuration.

    Cisco AST removes the actual deployed configuration from the devices, and the project moves to the draft state. You can start again from selecting the devices for pairing.

  2. Click Revert to revert to the baseline configuration.

  3. Click Accept to accept this configuration and click Apply to move the project to final tuned state.

    Cisco AST removes the actual configuration running, deploys the final configuration on the device, performs measurements, and generates the report.

  4. Click Restart to restart the tuning process from specifying the base properties.

  5. (Optional) Click Export Report to export the reports in the CSV format.

Done

The project moves to the Done state.

Base Configuration Properties

The following table describes the various properties that you have to provide for the baseline configuration.

Table 5. Base Configuration Properties

Parameter

Description

Minimum

Maximum

Default

Unit

Channel Power Rule

Selects the option for defining the power spectral density (PSD) at the OLS Add-Drop Module input.

The available options are:

  • Manual: In Manual mode, the input PSD is directly set as the RequiredPSD.

  • Derived: In Derived mode, the input PSD is derived from the Max Channel Power and the Max Channel BW.

In both modes, Cisco ASTpreserves the minimum average value of PSD that must be warranted over the link during the tuning process.

Manual, Derived

Manual, Derived

Derived

N/A

Max Channel Power

Maximum Channel Power of the Transponder output in dBm.

-20

23

+3dBm

dBm

Max Channel BW

Maximum Channel BW of the Transponder in GHz.

1

5000

72

GHz

Max Data Rate

Maximum line rate where Cisco AST searches for optimization. If this value is equal to the Min Data Rate, the search is performed only on the selected line rate. The valid value is 200, 250, 300, 350, and 400.

200

400

300

Gb/s

Min Data Rate

Minimum line rate where Cisco AST searches for optimization. If this value is equal to the max Data Rate, the search is performed only on the selected line rate. The valid value is 200, 250, 300, 350, and 400.

200

400

200

Gb/s

SNR Margin Target

Minimum SNR margin that must be warranted.

0

20

1

dB

SNR Margin Target Tol

SNR margin tolerance that limits the SNR margin target between a maximum and minimum SNR margin target range. The actual SNR margin tolerance comprises two values:

Actual SNR Margin Tolerance = Input Unequalization + Measure Error.

This parameter considers the maximum difference in the value of input channels PSD between any two adjacent channels that can impact the SNR margin target search.

0

10.00

0.05

dB

Required PSD

Minimum value of PSD that must be warranted at the OLS Add-Drop Module input in dBm/GHz.

-40

-15

-16

dBm/GHz

Start Frequency

Minimum frequency of the bandwidth allocated to the project. This field is mandatory.

191.3250

196.1250

191.3250

THz

Stop Frequency

Maximum frequency of the bandwidth allocated to the project. This field is mandatory.

191.3250

196.1250

196.1250

THz

Blocking Spectrum N Start Frequency

Minimum frequency of the forbidden bandwidth “N” to be used in the project.

191.3250

196.1250

191.3250

THz

Blocking Spectrum N Stop Frequency

Maximum frequency of the forbidden bandwidth “N” to be used in the project.

191.3250

196.1250

191.3250

THz

Width

Width of the Blocking Spectrum N starting from the Blocking Spectrum N Start Frequency of the forbidden bandwidth “N” to be used in the project. It is automatically derived by tool after setting Blocking Spectrum N Start Frequency and Blocking Spectrum N Stop Frequency.

N/A

N/A

N/A

THz

Mapping Granularity

Desired resolution of the tuning spectral map. The number shows how many carriers are used as probe for the tuning. (For example, when you select the value of mapping granularity as 3, one out of three carriers is used as a probe to perform the tuning.) This parameter also affects the interpolation granularity providing a flat region for every probe used for the tuning.

Note 

You can set the value of the granularity, based on which the baseline configuration is applied with respect to revert action.

You can set the following values for the Granularity:

  • Granularity is 1―The baseline configurations applied before the tuning and after the revert action, have homogenous carrier frequency configurations. The tuning goes in serial mode.

  • Granularity is 2―The baseline configurations applied before the tuning and after the revert action, have homogenous carrier frequency configurations. The tuning goes in serial mode.

  • Granularity is 3―The baseline configurations applied before the tuning and after the revert action, are different. The tuning goes in parallel mode.

1

3

3

N/A

OLS Add-Drop Constraints

Selects the type of SLTE implemented and affects the baseline generation. The available options are:

  • Limited―The Number Of Ports for each OLS Add-Drop Module are limited by the Required PSD.

  • Unlimited―No limitations are considered.

Limited, Unlimited

Limited, Unlimited

Unlimited

OLS Add-Drop Module Max Output Power

Maximum Output Power of the OLS Add-Drop Module in dBm. This parameter is used in Limited mode to calculate the Maximum Number Of Ports for each OLS Add-Drop Module provisionable with the required PSD.

-20.00

23.00

12 for Limited

dBm

Number Of Ports per OLS Add-Drop Module

Number of ports currently connected to the OLS Add-Drop Module device. This parameter is used ONLY in the Limited Mode to check if the Number Of Ports per OLS Add-Drop Module are enough to support the Required minimum required PSD at its input.

If the result is higher than the Required minimum PSD, the application proceeds with the configuration; otherwise, it warns you that the Number Of Ports per OLS Add-Drop Module exceeds the maximum number compared to the worst case.

The application also provides:

  • The maximum number of channels allowed with the current PSD: This is calculated according to the following formula:

    Number Of Ports per OLS Add-Drop Module ≤ [10^(OLS Add-Drop Module Max Output Power(dBm)/10)]/{72(GB)*[10^(Input PSD(dBm/GHz)/10)]}.

  • The minimum required input PSD to be set in the Manual Mode to allow usage of the current number of channels: The minimum required input PSD (in dBm/GHz) is derived according to the following formula:

    Input PSD(dBm/GHz) ≤ 10*log10{ [10^(OLS Add-Drop Module Max Output Power(dBm)/10)]/[Number Of Ports per OLS Add-Drop Module*72(GB)]}.

You can preserve the current Number Of Ports per OLS Add-Drop Module by setting the Required PSD parameter in the Manual Mode according to the value of PSD.

1

150

12 for Limited

N/A

Number Of OLS Add-Drop Module

Number of Mux/Demux devices used to aggregate the carriers. A Filtering Guardband (GBf) is required between each of them in order to avoid any filtering impairment.

1

20

8 for Limited

N/A

Grid Granularity

Value of the slice width of the Wavelength Selective Switch (WSS) units. The totla width of any group of channels (Media Channel (MCH) or equivalent) is multiple of this parameter.

1

100

6.25 for Limited and 12.5 GHz for Unlimited

GHz

Filtering Guard band

Value of the wasted BW due to filtering impairment at the edge of the MCH. Each MCH has one filtering guard band at each edge. (Two in total.) GBs is considered for each side.

The Modulation GB (GBm) describes the value of GB that must be observed among the channels, within the same MCH. In general, GBf is ≥ 0 GHz. When carriers are combined into an MCH, the different GBs are combined to obtain the MCH required bandwidths.

0

100

6.25 for Limited

GHz

Subsea Configuration Parameters

The following table explains the subsea configuration parameters.

Parameter

Description

Min

Max

Default

Unit

cd-max

Maximum chromatic dispersion.

–350000

+350000

+1000

ps/nm

cd-min

Maximum chromatic dispersion.

–350000

+350000

–1000

ps/nm

cpr-ext-win-mode

Carrier phase recovery extended window mode. The range is 1–9. Choose the value depending on the number of symbols. It can support up to 288 symbols for subsea and long-haul transmission over large dispersion and large effective area fiber.

1

9

8

N/A

cpr-win-mode

Carrier Phase Recovery Window Mode. The range is 1–4. Choose the value depending on the number of symbols. It can support up to 75 symbols for terrestrial regional, long-haul propagation over G.655 fiber type (small core diameter, low dispersion), or older submarine cable optimized for direct detect modulation.

1

4

1

N/A

cross-pol-gain-mode

Carrier Phase Recovery Cross Polarization Gain Mode.

The optimal value for subsea and long-haul transmission over large dispersion and large effective area fiber is in the range of 3–6.

The optimal value for terrestrial regional, long-haul propagation over G.655 fiber type (small core diameter, low dispersion), or older submarine cable optimized for direct detect modulation, is 0.

0

15

4

N/A

cross-pol-weight-mode

Carrier Phase Recovery Cross Polarization Weight Mode.

The optimal value for subsea and long-haul transmission over large dispersion and large effective area fiber is in the range of 3–6.

The optimal value for terrestrial regional or long-haul propagation over G.655 fiber type (small core diameter, low dispersion) or older submarine cable optimized for direct detect modulation, is in the range of 2–4.

1

7

4

N/A

enh-colorless-mode

Enhanced Colorless Mode.

In colorless Rx deployment, you must not set this parameter to Mode 0. The colorless interference penalty depends on many conditions; hence we recommend choosing mode 1–3 for each wavelength, by and determining the mode that provides the lowest BER. Typically, the edge channels (of a wavelength group) require only Mode 1, whereas the channels in the middle of each group need Mode 2 or 3.

In Colored Rx deployment, set this parameter to Mode 0.

1

3

3

N/A

enh-sop-tol-mode

Enhanced Second Order Polarization (SOP) Tolerance Mode.

In subsea deployment, we recommend setting this parameter to Mode 3 for enhanced sensitivity. In subsea, the polarization state is minimal, and you can use a reduced tracking rate to improve linear sensitivity. This bit can only be enabled in Low-Power state.

In terrestrial network with aerial fiber deployment, if the cable is optical ground wire (OPGW) and deployed in regions with potential lightning activity, we recommend setting this parameter to Mode 1. This setting slightly degrades back-to-back sensitivity but enables DSP to track much faster SOP events. In those types of deployments, we recommend using the highest baud rate possible and a payload rate that is less than or equal to 400G.

1

3

3

N/A

filter-roll-off-factor

Root Raised Cosine (RRC) Filter Roll-Off Factor.

In subsea, the goal is to maximize overall cable capacity. Therefore, you must pack as many wavelengths as you can on the fiber pair, with minimal spectral gaps between the channels.

We recommend using transmitter RRC pulse shape with roll-off factor of 0.07 to 0.085. This change can be made while in high-power state. Reducing the Tx roll-off factor usually generates a small back-to -back sensitivity penalty. However, in deployment, a reduced roll-off factor reduces the effect of neighboring channel interference.

0

1

0.074 (in steps of 0.001, length of string must be 5)

N/A

nleq-comp-mode

Configures the nonlinear compensation functionality and optimizes best performance over propagation.

For +D system with high dispersion large effective area fiber, set the value to the following value:

  • 1 for high baud rate (60Gbaud - 72Gbaud)

  • 2 for lower baud rates (30Gbaud > 55Gbaud)

Similarly, for small effective area and low dispersion fiber, set the value to the following value, to provide better performance with longer distance and higher accumulated dispersion:

  • 3 for high baud rate (60Gbaud -> 72Gbaud).

  • 4 for lower baud rates (30Gbaud -> 55Gbaud).

1

4

2

N/A

rx-voa-mode

Receive variable optical attenuation mode.

The available options are:

  • fixed-ratio

  • target-power

fixed-ratio

rx-voa-fixed-ratio

Receive Ratio of Optical Attenuation.

  • In colorless deployment, choose 17dB as the ratio.

  • In colored deployment, choose 15dB as the ratio.

.

1

17

17

dB

rx-voa-target-power

Receive Target Power.

  • In colorless deployment, choose 7dBm as the target power.

  • In colored deployment, choose 5dBm as the target power.

–19

+3

–7

dBm

Troubleshoot Cisco AST Issues Using Logs

You can troubleshoot any issues that you may encounter while using the Cisco AST application by reviewing the data available in the following logs:

Table 6. Cisco AST Logs

Logs

Description

Tech-Support Logs (for issues with licensing process)

The Smart Agent integrated with Cisco AST provides logs information regarding the licensing process.

  • Click the License icon in the left panel.

    The Smart Software Licensing page appears.

  • Click View under Tech-Support Logs.

    You can view the log information related to the licensing process.

  • Click Save as File to save the logs to a text format.

    You can share the file with the Cisco support team to troubleshoot any issues in the licensing process.

Tuner Intermediate Logs

You can troubleshoot the issues in a tuning project based on the tuner intermediate logs, such as the configuration data fetched and applied in the tuning process.

  • Click Projects in the left panel.

  • Under the Logs column, click the log icon corresponding to a project.

  • Click Open or Download to view or download the tuner intermediate logs.

Audit Logs

Audit logs display a historical record of events performed by users in the Cisco AST application.

  • Click Admin in the left panel.

  • Click Audit Logs.

    A table listing the type of events, description of the events, timestamps, and the user who triggered the events appears.

  • To filter the events, choose the Start Date and the End Date, and select the type of events from the Select Log Event drop-down list.

  • Click Export to download the audit log details in a compressed format (zip file) to your local system.

Troubleshooting Logs

The troubleshooting page is a centralized logging area that includes entire logs related to the services and components of a tuner project.

  • Click Troubleshooting in the left panel.

  • Click Download to download the logs in a CSV file format.

  • Click View to view service logs in the Kibana dashboard.

    Kibana is an open-source analytics and visualization platform. For information about Kibana, see https://www.elastic.co/products/kibana.

    You can filter the logs and download it from the Kibana page.