Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

How to Provision a Virtual Chassis Using the Phone-Home Client


Phone-home provisioning on a Virtual Chassis is a form of zero-touch provisioning (ZTP). The phone-home client (PHC) on the Virtual Chassis gets bootstrap information over the network from a phone-home server (PHS) and provisions the Virtual Chassis. The only user intervention required on the client side is to physically wire the Virtual Chassis members together and connect any port on the Virtual Chassis to the network.

Overview of Phone-Home Provisioning for a Virtual Chassis

With phone-home provisioning, a phone-home client (PHC) on a device initially provisions the device with a software image and configuration from a central network management data source called the phone-home server (PHS), requiring little or no user intervention at the remote site.

A Virtual Chassis consists of a set of devices interconnected together using ports called Virtual Chassis ports (VCPs). You configure and manage the Virtual Chassis as a single device. Starting with Junos OS Release 20.3R1, we’ve made extensions to the phone-home provisioning process for a standalone device so it can also work on a Virtual Chassis. The PHC on a Virtual Chassis requires extra steps to coordinate and manage bootstrapping the member devices.

The PHS is usually part of a network management system (NMS) that supports phone-home provisioning. Your network administrator enters the intended provisioning data that directs how devices and Virtual Chassis at remote sites should be set up. Your organization might have more than one PHS for redundancy.

You can check Feature Explorer and search for phone-home to see the Virtual Chassis platforms that support phone-home provisioning.

Benefits of Phone-Home Provisioning on a Virtual Chassis

  • Simplifies provisioning by launching the process automatically from the remote site, while securely obtaining bootstrap information from a central management system (the PHS) on your network or in the cloud.

  • Doesn’t require in-depth experience with the Junos OS CLI to coordinate the provisioning of multiple devices that make up a Virtual Chassis.

Overview of the Phone-Home Provisioning Process on a Virtual Chassis

On a Virtual Chassis that supports phone-home provisioning, for the process to work, you must set up the Virtual Chassis according to the requirements outlined in How To Enable Phone-Home Provisioning on a Virtual Chassis.

When the Virtual Chassis initially forms, the PHC process starts up automatically on the Virtual Chassis master member and takes it from there:

  1. The PHC connects to a PHS.

    The PHC sends a provisioning request to a default redirect server URL,, which redirects the request to an available PHS controlled by your network administrator or NMS. This step is the same as phone-home provisioning on a single device.

  2. The PHS responds to the PHC provisioning request with the bootstrapping information, which includes the intended Virtual Chassis topology, software image, and configuration.
  3. The PHC provisions the Virtual Chassis as specified by the PHS.

    Provisioning includes steps such as:

    • Validate the Virtual Chassis topology.

    • Upgrade the software image sequentially on all of the member devices if needed.

    • Run any pre-configuration or post-configuration staging scripts.

    • Commit a new configuration on the Virtual Chassis.

The PHC sends status notifications to the PHS during the bootstrapping process, so the network administrator can verify the process completes successfully.

The PHC also logs status locally in the system log files on the Virtual Chassis. If needed, you can view log files in the Junos OS CLI, and use Junos OS CLI commands to see Virtual Chassis and VCP connection status.

How To Enable Phone-Home Provisioning on a Virtual Chassis

On a Virtual Chassis that supports phone-home provisioning, if you set up the Virtual Chassis according to the steps listed here, a phone-home client (PHC) process starts up automatically on the Virtual Chassis master member.

To enable phone-home provisioning on a Virtual Chassis:

  1. Ensure that all Virtual Chassis members have the factory-default configuration and are powered off.

    You can run the request system zeroize Junos OS CLI command to return a device to its factory-default state.

  2. Interconnect the Virtual Chassis members in a ring topology using only dedicated or default-configured Virtual Chassis ports (VCPs) on each member device.

    Keep in mind that the PHC process works only if the Virtual Chassis is initially formed with VCPs that do not need to be explicitly configured (dedicated VCPs or ports that are VCPs in the factory-default configuration). See VCP Options by Switch Type for details on which ports are dedicated and default-configured VCPs on different devices that support Virtual Chassis. See the hardware guide for the device to locate those ports on the device.

  3. Connect the Virtual Chassis management interface (me0) or any network-facing port on any Virtual Chassis member to the network.

    After the PHC starts up on the Virtual Chassis, it uses this connection to access a PHS over the network and retrieve the bootstrapping information for this Virtual Chassis.

    For details about how the management interfaces work on a Virtual Chassis, see Understanding Global Management of a Virtual Chassis.

  4. Power on the members of the Virtual Chassis.

Figure 1 shows an example of a Virtual Chassis topology that can support phone-home provisioning—a four-member EX4300 Virtual Chassis cabled in a ring topology using default-configured VCPs (in this case, two of the 40-Gigabit Ethernet QSFP+ ports on each device).

Figure 1: Sample Virtual Chassis That Can Support Phone-Home Provisioning
Sample Virtual Chassis
That Can Support Phone-Home Provisioning

Usually you don’t need to do anything else for the phone-home provisioning process to proceed and complete successfully. If you don’t see successful completion status or the Virtual Chassis isn’t up and operating as expected at the end of the process, read on to learn details about how the PHC works to help troubleshoot the issues.


If provisioning completes successfully and your Virtual Chassis is up and running with the expected software version and configuration from your network management system, you’re done!

If you notice any unexpected results or want to know more about how the PHC works, see Provision a Virtual Chassis Using the Phone-Home Client. The details there can help you troubleshoot problems and track what’s going on during the process.