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Your Swiss army knife for NETCONF, YANG and NSO NEDs
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Jan Lindblad
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Your Swiss army knife for NETCONF, YANG and NSO NEDs.


Pioneer is a collection of tools that make the life in NSO easier when working in with NETCONF/YANG devices.

  • The NETCONF tools allow the NSO operator to issue simple NETCONF hello, get and get-config requests to the device to check basic NETCONF support.

  • The YANG tools allow the operator to build a NETCONF NED for the device, potentially disabling YANG models that fail to compile or operate correctly, or simply are out of scope.

  • The config tools allow working with device configuration using files, which is useful when debugging situations when the device configuration violates the device's YANG contract, and when testing transactionality properties.

  • The log tools allow reviewing the raw NETCONF communication between NSO and the device.

See usage examples below.

Note that Pioneer is intended for development work, and will not work properly on an NSO "system install".


Apart from this file, the main documentation is the pioneer.yang file, where each command is described. You may also want to have a look at Wai Tai's demo of Pioneer at


In order to run all of the functionality, you will need to have (in the path) the following components. If something is missing, your most important use cases may still work, but some tools will not.

  • NSO 4.1+
  • Python 2.7+ or 3.5+
  • Paramiko (SSH library for Python)
  • xsltproc
  • xmllint
  • bash
  • pyang from NSO

You can paste this command into a terminal to quickly check that all dependencies are fulfilled:

which ncs && which python && python -c "import paramiko" \
&& which xsltproc && which xmllint && which bash && which pyang \
&& echo "All Fine"

Build instructions

Normal NSO package build:

make -C packages/pioneer/src/ clean all


Only relevant if you are developing new features for Pioneer.

Lux test cases in the test/ directory. Run as

cd packages/pioneer/test/
lux internal

Usage examples


When you encounter a new NETCONF device for the first time, the first thing you need to do is to add it to the NSO device list under devices device.

Create an authgroup with login credentials for the device. Currently, Pioneer will only work with default-map, not umap.

devices authgroups group my-group
 default-map remote-name my-user-name
 default-map remote-password my-password

Create a device list entry for the device:

devices device my-netconf-device
 port            8300
 authgroup       my-group
 device-type netconf
 trace           raw
 state admin-state unlocked

Default port for NETCONF is 830. No need to specify port if the device is using that port. Trace may set to false, Pioneer does not depend on tracing being enabled.

Fetch the SSH host key from the device:

devices device my-netconf-device ssh fetch-host-keys

And commit all of this:


At this point, it should be possible to connect


Any attempt to sync-from will of course fail since we don't yet have a NETCONF NED for the device.

pioneer netconf hello

What we can do is to have a look at the hello message.

devices device my-netconf-device pioneer netconf hello

Which should give you a response along these lines:

<hello xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">

If connection fails, check your device list settings above and try again. If you want to remove NSO and Pioneer from the mix, you should get the above response from a Linux prompt if you ussue:

ssh user@address -p port -s netconf

pioneer netconf get, get-config

If hello repsonds correctly, you may want to try a simple get and get-config before proceeding to build a NETCONF NED. Here are the commands:

devices device my-netconf-device pioneer netconf get
devices device my-netconf-device pioneer netconf get-config

YANG tools

Let's build a NETCONF NED for the device.

pioneer yang fetch-list, download

First we need to get our hands on the YANG models describing the NETCONF interface for the device. The best way is to download them directly from the device. This way we ensure we have the right version for the device.

devices device my-netconf-device pioneer yang fetch-list
devices device test1a pioneer yang download

This should give us a list of YANG files supported by the device. Pioneer tries to get this list in three different ways, the hello message (incomplete list, but better than nothing), netconf-monitoring get-schema operation using xpath and subtree filtering. The second command will attempt to download them from the device. If this doesn't work, then you need to contact the supplier of the device and ask for the appropriate YANG modules (of the correct version).

pioneer yang build-netconf-ned

After the files have been downloaded they must built before they can be used. For NSO versions prior to 4.2 all NSO built-in YANG models needs to be disabled, see “Circular dependency for module ‘tailf-ncs’” below for details.

devices device my-netconf-device pioneer yang build-netconf-ned
Build complete. Run install-netconf-ned, then run 'packages reload' to use the package
ned-directory /tmp/packages/my-netconf-device

pioneer yang disable, enable

If not all YANG models are required or if any contain errors they can be disabled using pioneer yang disable. The following example shows how to disable the module broken from the build:

devices device my-netconf-device pioneer yang disable name-pattern broken
Disabling module broken

You can use wild-cards "broken*" or list multiple names inside double quotes separated with space "broken-module-1 broken-module-2".

If you would like to re-enable a module that you have disabled, you can use the enable command in a similar way.

devices device my-netconf-device pioneer yang enable name-pattern broken

pioneer yang show-list, delete

Use show-list to show which YANG modules are currently available, and which state they are in (enabled, disabled).

devices device my-netconf-device pioneer yang show-list

You may also delete YANG files that you don't want at all, i.e. in order to download it again.

devices device my-netconf-device pioneer yang delete name-pattern broken

pioneer yang check-dependencies

YANG modules often refer to one another (using import and include). A YANG module that refers to another module which has been disabled, deleted or never downloaded will not compile, and will have to be disabled. To find out about dependencies between YANG modules, run check-dependencies.

devices device my-netconf-device pioneer yang check-dependencies

When you have a consistent set of enabled YANG files, you can try building it again using the build-netconf-ned command.

pioneer yang install-netconf-ned, uninstall-netconf-ned

Once the netconf-ned is built, you need to install it into the running NSO runtime directory. Use the install-netconf-ned to do that.

devices device my-netconf-device pioneer yang install-netconf-ned

In order to make NSO use the new package, you also need to run a packages reload.

packages reload

If you don't want the netconf-ned in your packages directory any more, you can uninstall it. To actually unload it from NSO, you need to run packages reload again.

devices device my-netconf-device pioneer yang uninstall-netconf-ned
packages reload

Config tools

As the NETCONF NED is up and running, it's time to start using the device from NSO.

Let's go into configuration mode


The first thing to do is a sync-from. With the new NETCONF NED loaded, this should now work.

devices device my-netconf-device sync-from

pioneer config sync-from-into-file

If the sync-from doesn't work, there may be a number of different reasons. One of the most common ones is that the device has configuration data on board that violates the YANG specification of valid data. NSO will not load data from such liars!

In order to find out what data this may be, the sync-from-into-file command is useful. It gets the (potentially invalid) configuration from the device and stores it into a local file. You can then proceed to load and edit this file until the violation(s) are removed. This exercise will give you a good idea about how to change the device configuration so that it conforms to the YANG, and what error to report to the device vendor.

If you would like to inspect the contents of a file from the NSO configuration mode, you can do that using the command

do file show my-filename

There is no built-in way to edit files, however.

When NSO loads from a file, it employs "strict loading", which means that any unexpected elements will be rejected. When NSO runs a sync-from, it employs "lax loading", which accepts+ignores any unexpected elements in the data.

Because of this, it is often useful to sync-from-into-file and then load the file, just to ensure NSO doesn't silently drop any data coming from the device.

devices device my-netconf-device pioneer config \
 sync-from-into-file filename my-device-config.xml
load merge my-device-config.xml

A variant of this command saves the configuration as a device template instead, which you can edit and reuse later.

devices device my-netconf-device pioneer config \
 sync-from-into-file as-template my-template \
 filename my-device-template.xml
load merge my-device-template.xml
devices device my-netconf-device apply-template \
 template-name my-template

pioneer config import-into-file

Sometimes we get XML config files for a device that we would like to load into NSO. This does not work straight off, since in NSO the device configuration sits under "devices device config" of a particular device. The import-into-file command can take such a device XML file and generate a new file that loads nicely into NSO.

Config tools for testing device transactionality

Apart from testing some basic NETCONF operations and building NETCONF NEDs, Pioneer can also be used to test that a device support the proper transactional behavior. Among other things, transactional behavior means that a device can accept any valid configuration regardless of the state it is in currently. For all transactions it must also be true that the device configuration becomes exactly the previous configuration modified by the transaction. In other words, it's not acceptable that a device modifies any other parts of the configuration than the ones touched by the transaction.

Pioneer can test the conformance with these rules automatically, but requires a smart selection of input configurations in order to find something useful. This is how it is done.

pioneer config record-state, list-states, delete-state

Configure the device to an interesting configuration state, and make sure NSO is in sync with the device. Changes may be entered directly on the device, followed by a sync-from in NSO. Or changes may be entered in NSO and committed to the device. Once a configuration is running fine on the device and NSO is in sync, issue the operational command:

devices device <device-name> pioneer config record-state state-name <state-name>

The state name needs to be a valid file name, but can otherwise be chosen freely. The name will be used later to describe which configuration state transitions that have issues.

Keep doing this with interesting configurations for a while, so that you have at least 4 states recorded, up to maybe a few dozens. You can list the names of the states you have recorded, or delete ones you don't want to keep using:

devices device <device-name> pioneer config list-states
devices device <device-name> pioneer config delete-state state-name <state-name>

pioneer config explore-transitions

Then, when enough states have been collected, Pioneer can start testing that all transitions work flawlessly. By default all transitions are tried. That should give a safe result. Since testing all-to-all configuration transitions grows exponentially with the number of states, it's also possible to limit the number of transitions to try out. The test will then not be conclusive, but maybe more reasonable to run. You can run start the test in any of these ways:

devices device <device-name> pioneer config explore-transitions
devices device <device-name> pioneer config explore-transitions stop-after { seconds 30 }
devices device <device-name> pioneer config explore-transitions stop-after { minutes 5 }
devices device <device-name> pioneer config explore-transitions stop-after { hours 12 }
devices device <device-name> pioneer config explore-transitions stop-after { days 2 }
devices device <device-name> pioneer config explore-transitions stop-after { cases 20 }
devices device <device-name> pioneer config explore-transitions stop-after { percent 10 }

The sequence of transitions to try is selected randomly. Two different runs will therefore not yield the same test pattern.

A test run might look like this:

admin@ncs# devices device xr pioneer config explore-transitions stop-after { percent 10 }
Found 8 states recorded for device xr which gives a total of 56 transitions.

Starting from known state noloop8
... failed setting known state

Starting from known state bundle-vrf
Transition 1/56: bundle-vrf ==> bundle-vrf-ipv4
Transition 2/56: bundle-vrf-ipv4 ==> bundle-vrf-ipv46
Transition 3/56: bundle-vrf-ipv46 ==> bundle-vrf-ipv4
Transition 4/56: bundle-vrf-ipv4 ==> bundle-vrf
Transition 5/56: bundle-vrf ==> bundle-vrf-ipv46
Transition 6/56: bundle-vrf-ipv46 ==> bundle-vrf
Requested stop-after time limit reached
success Completed successfully

The comment "...failed setting known state" is an indication that something isn't right. But since Pioneer didn't know exactly what state the device was in before we started (or after a transaction has failed) it's hard to give instructions on how to repeat the issue, so this problem is ignored.

If an issue is found, the outcome might look like this:

admin@ncs# devices device xr pioneer config explore-transitions stop-after { percent 10 }
Found 8 states recorded for device xr which gives a total of 56 transitions.

Starting from known state bundle-vrf-ipv4
Transition 1/56: bundle-vrf-ipv4 ==> bundle-vrf-ipv46
Transition 2/56: bundle-vrf-ipv46 ==> bundle-vrf-ipv4
Transition 3/56: bundle-vrf-ipv4 ==> bundle-vrf
Transition 4/56: bundle-vrf ==> bundle-vrf-ipv4
Transition 5/56: bundle-vrf-ipv4 ==> initial

Starting from known state no-bundle-ipv46
Transition 6/56: no-bundle-ipv46 ==> bundle-vrf-ipv4
Requested stop-after coverage limit reached
failure transaction-failed: bundle-vrf-ipv4 ==> initial

Here, the transition from state bundle-vrf-ipv4 to initial failed. 'transaction-failed' means the device refused to go between these two states. If you'd see 'out-of-sync', that means the transaction was accepted by the device, but the configuration of the device is different than expected. Usually this means the device created/changed some other values than the ones specified in the transaction. In any case, the device configuration isn't what it should be. Assuming netconf tracing was enabled, this failure can now be debugged by manually invoking the configuration states in question:

devices device <device-name> pioneer config transition-to-state state-name <state-name>
admin@ncs# devices device xr pioneer config transition-to-state state-name bundle-vrf-ipv4
success Done
admin@ncs# devices device xr pioneer config transition-to-state state-name initial        
failure transaction-failed
admin@ncs# file show logs/netconf-xr.trace 
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
  <edit-config xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
      <interface-configurations xmlns="">
    <error-message xml:lang="en">'RSI' detected the 'fatal' condition 'The interface's numbered and unnumbered IPv4/IPv6 addresses must be removed prior to changing or deleting the VRF'</error-message>

Clearly, a violation of the transactional behavior. The device may also have log files worth looking at to understand the issue.


Circular dependency for module ‘tailf-ncs’

Files that are already part of NSO must not be included in the YANG files when building a NED. This includes

  • ietf-inet-types
  • ietf-yang-types
  • tailf-*

If one of the above files is included an error like the one below will appear when building a NED from the YANG model:

augmented/ietf-inet-types@2013-07-15.yang:8: error: circular dependency for module 'tailf-ncs'
augmented/ietf-yang-types@2013-07-15.yang:8: error: circular dependency for module 'tailf-ncs'

Fix this by disabling the files with the issue and building the NED again.

devices device my-netconf-device pioneer yang disable name-pattern ietf-*-types
Disabling module ietf-inet-types


Contact Jan Lindblad with any suggestions or comments.

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