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README v1.0.0 2026-09-02

Table of contents

1. General
   1.1 Extract the NED package
   1.2 Install the NED package
       1.2.1 Local install
       1.2.2 System install
   1.3 Configure the NED in NSO
2. Optional debug and trace setup
3. Dependencies
4. Sample device configuration
5. Built in RPC actions
   5.1. rpc add-filter-path
   5.2. rpc clean-package
   5.3. rpc clear-cached-capabilities
   5.4. rpc clear-filter-paths
   5.5. rpc compare-config
   5.6. rpc compare-loaded-schema
   5.7. rpc compile-modules
   5.8. rpc export-package
   5.9. rpc get-modules
   5.10. rpc import-filter-paths
   5.11. rpc list-filter-paths
   5.12. rpc list-module-sets
   5.13. rpc list-modules
   5.14. rpc list-profiles
   5.15. rpc patch-modules
   5.16. rpc rebuild-package
   5.17. rpc remove-filter-path
   5.18. rpc show-default-local-dir
   5.19. rpc show-loaded-schema
   5.20. rpc verify-get-config
   5.21. rpc xpath-trace-analyzer
6. Built in live-status show
7. Limitations
8. How to report NED issues and feature requests
9. How to rebuild a NED
10. Configure the NED to use ssh multi factor authentication
11. Using the NED for Telemetry
12. Run arbitrary commands on device

1. General

This document describes the harmonic-cableos_nc NED.

IMPORTANT: This NED is delivered without any of the device YANG models bundled to the NED package.

It is required to download the YANG files separately and rebuild the NED package before the NED is fully operational. See the README-rebuild.md for further information.

In summary, the below steps are needed to have a fully functioning NED:

Additional README files bundled with this NED package

Common NED Features

Verified target systems

1.1 Extract the NED package

It is assumed the NED package ncs-<NSO version>-harmonic-cableos_nc-<NED version>.signed.bin has already been downloaded from software.cisco.com.

In this instruction the following example settings will be used:

  • NSO version: 6.0

  • NED version: 1.0.1

  • NED package downloaded to: /tmp/ned-package-store

  1. Extract the NED package and verify its signature:

  2. In case the signature can not be verified (for instance if no internet connection), do as below instead:

  3. The result of the extraction shall be a tar.gz file with the same name as the .bin file:

1.2 Install the NED package

There are two alternative ways to install this NED package. Which one to use depends on how NSO itself is setup.

In the instructions below the following example settings will be used:

  • NSO version: 6.0

  • NED version: 1.0.1

  • NED download directory: /tmp/ned-package-store

  • NSO run time directory: ~/nso-lab-rundir

A prerequisite is to set the environment variable NSO_RUNDIR to point at the NSO run time directory:

IMPORTANT:

This NED is delivered as an “empty” package, i.e without any device YANG models bundled. It must be rebuilt with the device YANG models to become operational.

The procedure to rebuild the empty NED (described in the README-rebuild.md) shall typically be done in a lab environment. For this step a “local install” of the NED shall be used. It is not suitable to use “system install” here since it is intended for production systems only.

Once this NED has been rebuilt with the device YANG and exported to one or many separate tar.gz customized NED packages, a “system installation” can be used on them.

1.2.1 Local install

This section describes how to install a NED package on a locally installed NSO (see "NSO Local Install" in the NSO Installation guide).

It is assumed the NED package has been been unpacked to a tar.gz file as described in 1.1.

  1. Untar the tar.gz file. This creates a new sub-directory named: harmonic-cableos_nc-<NED major digit>.<NED minor digit>:

  2. Install the NED into NSO, using the ncs-setup tool:

  3. Open a NSO CLI session and load the new NED package like below:

Alternatively the tar.gz file can be installed directly into NSO. Then skip steps 1 and 2 and do like below instead:

Set the environment variable NED_ROOT_DIR to point at the NSO NED package:

1.2.2 System install

This section describes how to install a NED package on a system installed NSO (see "NSO System Install" in the NSO Installation Guide).

It is assumed the NED package has been been unpacked to a tar.gz file as described in 1.1.

  1. Do a NSO backup before installing the new NED package:

  2. Start a NSO CLI session and fetch the NED package:

  3. Install the NED package (add the argument replace-existing if a previous version has been loaded):

  4. Load the NED package

1.3 Configure the NED in NSO

This section describes the steps for configuring a device instance using the newly installed NED package.

  • Start a NSO CLI session:

  • Enter configuration mode:

  • Configure a new authentication group (my-group) to be used for this device:

  • Configure a new device instance (example: dev-1):

    IMPORTANT:

    The device-type shall always be set to generic when configuring a device instance to use a 3PY NED. A common mistake is configuring it as netconf, which will cause NSO to use its internal netconf client instead.

  • Finally commit the configuration

  • Verify configuration, using a sync-from.

If the sync-from was not successful, check the NED configuration again.

2. Optional debug and trace setup

It is often desirable to see details from when and how the NED interacts with the device(Example: troubleshooting)

This can be achieved by configuring NSO to generate a trace file for the NED. A trace file contains information about all interactions with the device. Messages sent and received as well as debug printouts, depending on the log level configured.

NSO creates one separate trace file for each device instance with tracing enabled. Stored in the following location:

$NSO_RUNDIR/logs/ned-harmonic-cableos_nc-gen-1.0-<device name>.trace

Do as follows to enable tracing in one specific device instance in NSO:

  1. Start a NSO CLI session:

  2. Enter configuration mode:

  3. Enable trace raw:

    Alternatively, tracing can be enabled globally affecting all configured device instances:

  4. Configure the log level for printouts to the trace file:

    Alternatively the log level can be set globally affecting all configured device instances using this NED package.

The log level 'info' is used by default and the 'debug' level is the most verbose.

IMPORTANT: Tracing shall be used with caution. This feature does increase the number of IPC messages sent between the NED and NSO. In some cases this can affect the performance in NSO. Hence, tracing should normally be disabled in production systems.

An alternative method for generating printouts from the NED is to enable the Java logging mechanism. This makes the NED print log messages to common NSO Java log file.

$NSO_RUNDIR/logs/ncs-java-vm.log

Do as follows to enable Java logging in the NED

  1. Start a NSO CLI session:

  2. Enter configuration mode:

  3. Enable Java logging with level all from the NED package:

  4. Configure the NED to log to the Java logger

    Alternatively Java logging can be enabled globally affecting all configured device instances using this NED package.

IMPORTANT: Java logging does not use any IPC messages sent to NSO. Consequently, NSO performance is not affected. However, all log printouts from all log enabled devices are saved in one single file. This means that the usability is limited. Typically single device use cases etc.

SSHJ DEBUG LOGGING For issues related to the ssh connection it is often useful to enable full logging in the SSHJ ssh client. This will make SSHJ print additional log entries in $NSO_RUNDIR/logs/ncs-java-vm.log:

3. Dependencies

This NED has the following host environment dependencies:

  • Java 1.8 (NSO version < 6.2)

  • Java 17 (NSO version >= 6.2)

  • Gnu Sed

Dependencies for NED recompile:

  • Apache Ant

  • Bash

  • Gnu Sort

  • Gnu awk

  • Grep

  • Python3 (with packages: re, sys, getopt, subprocess, argparse, os, glob)

4. Sample device configuration

NONE

5. Built in RPC actions

5.1. rpc add-filter-path

5.2. rpc clean-package

5.3. rpc clear-cached-capabilities

5.4. rpc clear-filter-paths

5.5. rpc compare-config

5.6. rpc compare-loaded-schema

5.7. rpc compile-modules

5.8. rpc export-package

5.9. rpc get-modules

5.10. rpc import-filter-paths

5.11. rpc list-filter-paths

5.12. rpc list-module-sets

5.13. rpc list-modules

5.14. rpc list-profiles

5.15. rpc patch-modules

5.16. rpc rebuild-package

5.17. rpc remove-filter-path

5.18. rpc show-default-local-dir

5.19. rpc show-loaded-schema

5.20. rpc verify-get-config

5.21. rpc xpath-trace-analyzer

Configuration of CLI interaction through 'live-status exec any '.

In case the default values are different, set these ned-settings before using live-status actions:

ned-settings harmonic-cableos_nc live-status cli port 22 ned-settings harmonic-cableos_nc live-status cli prompt-pattern "^[\w@]+((\w+))?[>#][ ]*$" ned-settings harmonic-cableos_nc live-status cli no-pagination-cmd "paginate false" commit

ned-settings harmonic-cableos_nc live-status cli auto-prompts 1 question "(?is)reboot.warning.?\s*[\syes\s[/,]\sno\s]\s*[:\s]$" answer no ned-settings harmonic-cableos_nc live-status cli auto-prompts 2 question "(?i).?\s*[\syes\s[/,]\sno\s]\s*[:\s]*$" answer yes commit

To use the NED for live-status commands only, set the following ned-setting:

ned-settings harmonic-cableos_nc connection connection-mode live-status-only commit

6. Built in live-status show

NONE

7. Limitations

NONE

8. How to report NED issues and feature requests

Issues like bugs and errors shall always be reported to the Cisco NSO NED team through the Cisco Support channel:

The following information is required for the Cisco NSO NED team to be able to investigate an issue:

Do as follows to gather the necessary information needed for your device, here named 'dev-1':

  1. Enable full debug logging in the NED

  2. Configure the NSO to generate a raw trace file from the NED

  3. If the NED already had trace enabled, clear it in order to submit only relevant information

    Do as follows for NSO 6.4 or newer:

    Do as follows for older NSO versions:

  4. Run a compare-config to populate the trace with initial device config

  5. Reproduce the found issue using ncs_cli or your NSO service. Write down each necessary step in a reproduction report.

  6. Gather the reproduction report and a copy of the raw trace file containing data recorded when the issue happened.

  7. Contact the Cisco support and request to open a case. Provide the gathered files together with access details for a device that can be used by the Cisco NSO NED when investigating the issue.

Requests for new features and extensions of the NED are handled by the Cisco NSO NED team when applicable. Such requests shall also go through the Cisco support channel.

The following information is required for feature requests and extensions:

  1. A detailed use case description, with details like:

    • Data of interest

    • The kind of operations to be used on the data. Like: 'read', 'create', 'update', 'delete' and the order of the operation

    • Device APIs involved in the operations (For example: REST URLs and payloads)

    • Device documentation describing the operations involved

  2. Run sync-from # devices device dev-1 sync-from (if relevant)

  3. Attach the raw trace to the ticket (if relevant)

  4. Access to a device that can be used by the Cisco NSO NED team for testing and verification of the new feature. This usually means that both read and write permissions are required. Pseudo access via tools like Webex, Zoom etc is not acceptable. However, it is ok with access through VPNs, jump servers etc.

9. How to rebuild a NED

Check the README-rebuild.md file, chapter 1.3, for more information.

10. Configure the NED to use ssh multi factor authentication

This NED supports multi factor authentication (MFA) using the ssh authentication method 'keyboard-interactive'.

Some additional steps are required to enable the MFA support:

  1. Verify that your NSO version supports MFA. This is configurable as additional settings in the authentication group used by the device instance.

    Enter a NSO CLI and enter the following and do tab completion:

    If 'mfa' is displayed in the output like above, NSO has MFA support enabled. In case MFA is not supported it is necessary to upgrade NSO before proceeding.

  2. Implement the authenticator executable. The MFA feature relies on an external executable to take care of the client part of the multi factor authentication. The NED will automatically call this executable for each challenge presented by the ssh server and expects to get a proper response in return.

    The executable can be a simple shell script or a program implemented in any programming language.

    The required behaviour is like this:

    • read one line from stdin The line passed from the NED will be a semi colon separated string containing the following info:

      The elements for device name, user, password and opaque corresponds to what has been configured in NSO. The ssh server name, instruction and prompt are given by the ssh server during the authentication step.

      Each individual element in the semi colon separated list is Base64 encoded.

    • Extract the challenge based on the contents above.

    • Print a response matching the challenge to stdout and exit with code 0

    • In case a matching response can not be given do exit with code 2

    Below is a simple example of an MFA authenticator implemented in Python3:

  3. Configure the authentication group used by the device instance to enable MFA. There are two configurables available:

    • executable The path to the external multi factor authentication executable (mandatory).

    • opaque Opaque data that will passed as a cookie element to the executable (optional).

  4. Try connecting to the device.

10.1 Trouble shooting

In case of connection problems the following steps can help for debugging:

Enable the NED trace in debug level:

Try connect again

Inspect the generated trace file.

Verify that the ssh client is using the external authenticator executable:

Verify that the executable is called with the challenges presented by the ssh server:

Check for any errors reported by the NED when calling the executable

11. Using the NED for Telemetry

Introduction

This NED supports subscribing to telemetry events using the telemetry feature introduced in NSO 6.7. With this capability, NSO can act as a telemetry subscriber towards managed devices, enabling powerful automation patterns at the service layer — such as feedback loops that provision configuration on a device and then automatically react when that configuration becomes active.

Prerequisites

  • The NED is used together with NSO 6.7 or newer.

  • The managed device supports the YANG-Push (RFC 8641) extension for NETCONF.

Restrictions

The NSO telemetry feature is designed to assist with provisioning — for example, by receiving automatic notifications when a provisioned configuration becomes active. It is generally not intended for high-frequency telemetry data reception.

Background: YANG-Push (RFC 8641)

YANG-Push is an IETF-standardized protocol defined in RFC 8641. It extends the NETCONF and RESTCONF protocols with the ability for a client to establish subscriptions on a YANG datastore, causing the device to stream updates back to the subscriber without repeated polling.

YANG-Push builds on the concepts introduced in the Subscription to YANG Notifications framework (RFC 8639) and supports two complementary subscription modes:

Mode
Behavior

Periodic

The device sends a complete snapshot of all data under the subscribed path at a fixed interval. Useful for counters, statistics, and any data that changes frequently and continuously.

On-Change

The device sends an update only when something changes under the subscribed path. Useful for configuration state, session tables, or protocol status fields where changes are discrete events. Note that not all devices support on-change subscriptions across every part of their schema.

Key characteristics of the protocol include:

  • Datastore awareness — Subscriptions target a specific YANG datastore (e.g., running, operational, candidate), giving precise control over what kind of data is observed.

  • Filtering — Subscriptions can be narrowed using XPath or subtree filters so that only relevant portions of the datastore are streamed.

  • Dampening — On-change subscriptions support a dampening period that aggregates rapid-fire changes into fewer, consolidated updates.

  • Sync-on-start — On-change subscriptions can optionally deliver a full initial snapshot when the subscription is first established, ensuring the subscriber has a known baseline.

By leveraging YANG-Push through this NED, NSO gains a real-time, event-driven view of device state — a foundation for building closed-loop automation and reactive service logic.

Configuring a Telemetry Subscription

Telemetry subscriptions are configured under each device's telemetry container:

You can set up one or more subscriptions per device. Each subscription must specify, at a minimum, a datastore, a subscription mode (periodic or on-change), and a path (XPath or subtree filter) pointing to the location of interest in the device schema.

General YANG-Push Subscription Settings

Setting
Description

name

Subscription name (used as the list key).

local-user

The NSO user whose authentication credentials are used when connecting to the device for the telemetry session.

datastore

Target datastore to subscribe to (e.g., running, operational).

xpath

XPath filter pointing to the path of interest in the device schema.

subtree

Subtree filter — an alternative to xpath for specifying the path of interest.

periodic

Enables periodic mode. The device sends a full snapshot of data under the subscribed path at regular intervals.

periodic/period

Update interval in centiseconds. Mandatory when using periodic mode.

periodic/anchor-time

Optional anchor time for aligning the periodic interval.

on-change

Enables on-change mode. The device sends an update only when a node under the subscribed path has changed. Note that on-change may only be supported for certain parts of the device schema.

on-change/dampening-period

Minimum time between consecutive updates, in centiseconds.

on-change/sync-on-start

Whether to send a full synchronization snapshot when the subscription is first established. Default: true.

on-change/excluded-change

Change types to exclude from notifications: create, delete, insert, move, replace.

reconnect-interval

How often (in seconds) to retry a failed subscription. Default: 60.

setting

A list of key/value pairs for NED-specific settings (see below).

NED-Specific Settings

The following settings are configured in the setting list. Because this list accepts arbitrary key/value string pairs, it is important that both keys and values are spelled exactly as shown below.

Key
Description

rate-limit-period

Rate-limit period in centiseconds. When set, the NED ensures that telemetry messages are not forwarded to NSO more frequently than this interval. This is intended as a safeguard against excessively high-frequency updates (e.g., from a misbehaving device). Disabled by default.

rate-limit-drop-log-interval

Controls how often dropped telemetry events are logged when rate limiting is active. Default: 50.

force-raw

When set to true, the NED delivers telemetry events to NSO as raw, unparsed YANG-Push messages instead of model-driven data. By default, telemetry events are parsed by NSO and populated into a synthetic transaction, which allows services to perform standard operations such as diff iteration using the Maagic API. In some cases it may be preferable to receive the raw data and handle parsing in the service itself. When raw mode is active, the data is made available at: /devices/device/<name>/telemetry/subscription/<name>/raw-telemetry

Examples

The following examples show how to configure telemetry subscriptions through the NSO CLI.

Example 1: On-Change Subscription with Rate Limiting

This subscription monitors the interfaces subtree in the running datastore and applies a rate limiter to prevent excessive updates.

Example 2: Periodic Subscription with Raw Delivery

This subscription polls the interfaces subtree in the operational datastore every 10 seconds (1000 centiseconds) and delivers the data as raw YANG-Push messages.

Using Telemetry in Service Applications

This section provides an overview of how telemetry can be integrated into service applications to assist with provisioning and monitoring. For full details, refer to the NSO documentation.

Toolkit Components

The service developer's toolkit for working with telemetry consists of two main components:

  1. Synthetic Telemetry Transactions

    • For model-driven telemetry events, NSO fully populates the received data into a synthetic transaction. This means you can use standard NSO API operations — such as diff iteration and the Python Maagic API — to inspect and react to the data.

    • For raw telemetry events, the unparsed data can be read from the synthetic transaction at: /devices/device/<name>/telemetry/subscription/<name>/raw-telemetry

  2. Telemetry Kickers

    • The telemetry-kicker (configured under /kickers) lets you trigger an action whenever a telemetry event is received that matches a selector expression. This is the primary mechanism for wiring telemetry events into your service logic.

Together, these components enable patterns such as:

  • Feedback-loop provisioning — Push configuration to a device, then automatically detect when it has taken effect.

  • Alarm propagation — React to operational state changes on the device and propagate them northbound.

Example: Feedback-Loop Based BGP Provisioning

The following example demonstrates a very simple service application that provisions a BGP neighbor on a device and uses telemetry to detect when that neighbor reaches the ESTABLISHED state. When the telemetry event is received, the service automatically updates an operational leaf, which in turn can notify northbound systems (for instance, via a northbound YANG-Push subscription from NSO).

Service YANG Model

Service Python module

How it works:

  1. When the service is created, it configures a telemetry kicker and an on-change telemetry subscription targeting the BGP group on the device.

  2. As the device detects a change in the subscribed BGP group, it pushes an update to NSO via YANG-Push.

  3. The telemetry kicker fires and invokes the handle-autonomous-bgp-notification action.

  4. The action inspects the synthetic transaction to check whether the BGP neighbor has reached the ESTABLISHED state.

  5. If so, the action removes the subscription and kicker (cleanup) and sets the service's operational-state leaf to ESTABLISHED.

  6. Northbound systems subscribed to NSO can then be notified of this state change automatically.

12. Run arbitrary commands on device

Some commands that are available to a user logged in to an interactive CLI session on the device might not be available through NETCONF. For situations like this the NED provides the feature to run arbitrary commands through an interactive SSH login to the device. This SSH session is handled internally in the NED and connected in NSO to a live-status action called 'exec any'.

There are some ned-settings to control the behaviour of this feature, see the section 'ned-settings harmonic-cableos_nc live-status cli' in README-ned-settings.md for details on this.

Specifically, to be able to handle the interactive session towards the device, the NED needs to know the format for the device prompt. It also assumes that pagination is turned off before reading output from command sent (i.e. that the device doesn't pause terminal output, waiting for interactive response). The ned-settings 'prompt-pattern' and 'no-pagniation-cmd' are used to control this. These might have proper default values, please check that this matches your device though before trying this feature, since if not configured correctly the NED will hang until timed out.

As an example, to run the command 'show running-config' on the device, and get the resulting output as a string from the ncs_cli, run the following:

Note that when using ncs_cli, the command-line given might need to be quoted if it contains characters that are interpreted by the ncs_cli itself.

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