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Create a Greenfield Deployment For a New Data Center Network


This section shows how to perform zero-touch provisioning to build a new data center fabric from scratch (sometimes called a greenfield deployment) To do so, we are using Contrail Command, the user interface for CEM.

Figure 1 shows the edge-routed bridging topology that we will use in this example.

Figure 1: Greenfield Deployment on Edge-Routed Bridging Topology
Greenfield Deployment on Edge-Routed
Bridging Topology

Before You Begin

Before you begin building a new fabric, you need to do a few tasks.

Information to Obtain

  • IP address ranges for your management network, fabric interfaces, and loopback interfaces.

  • Autonomous system (AS) number for the iBGP fabric overlay

  • AS number range for eBGP in the fabric underlay

  • Serial numbers of the devices in your fabric.

Cable Your Devices

Connect the interfaces between the fabric devices. Make sure to connect all leaf devices to all spine devices, and all spine devices to all leaf devices.

Do not connect similar devices to each other. For example, do not connect a cable between one leaf device and another leaf device, nor between two spine devices.

Cable Your Management Network

Cable the management network including all of the devices that will be in the data center fabric. The resulting out-of-band (OoB) management network should include the fabric devices and the Contrail Cluster components.

Install Contrail Software

You need to connect a server to your management network and install Contrail software. See Installing Contrail Command and Installing a Contrail Cluster Using Contrail Command.

Create YML File

You must create a file in .yml format that is uploaded to Contrail as part of the process of creating a fabric. You can use Contrail Command to first download a generic template to edit with the specifics of your installation.

The .yml file must contain the serial numbers of all devices to which ZTP is performed.

You can also include hostnames in your file, and the hostnames are assigned for your devices during ZTP. If you don’t specify hostnames, Contrail Software uses the serial number of the device.

A device information .yml file that assigns hostnames is in the following format:

You can also specify a JunOS image release version, and devices will be upgraded to that version during ZTP.

Put Fabric Devices in a Factory-Default State

Make sure the fabric devices have not been configured and are in a zeroized, factory-default state and bring them online.

To place devices in a factory-default state, enter the request system zeroize command at the Junos OS CLI.

Junos OS devices display Amnesiac on the login screen when in the proper state.

Figure 2: Junos OS in Zeroized State
Junos OS in Zeroized State

Creating the New Fabric and Discovering Devices

Once you complete the tasks in Before You Begin you can use zero-touch provisioning to create a new data center fabric and launch the device discovery process. To begin:

  1. Open a web browser, navigate to the Contrail Command URL, enter your user name and password, and click Log in.

    The format for the Contrail Command URL is https://contrail-command-server-ip-address:9091. 9091 is the port that gives you access to Contrail Command.

    Contrail Command displays a status dashboard as the home page.

  2. Navigate to Infrastructure > Fabrics and click Create.
    Figure 3: Select Provisioning Option
    Select Provisioning Option
  3. Select New Fabric and click Provision.
  4. Configure the following fields:



    Value used in this example


    Name of your fabric


    Device credentials

    Root password for your fabric devices


    Overlay ASN (iBGP)

    Autonomous system number for the EVPN overlay (Default is 64512)


    Device Info

    In this step you upload your .yml file that has your device serial numbers as well as optional supplemental configuration, such as hostnames.

    Click Upload .yaml or .yml, select your file, and click open.


    Node profiles

    Device types that are available in your greenfield data center fabric

    Use the default, which enables all node profiles.

    VLAN-ID Fabric-Wide Significance

    Select the VLAN-ID Fabric Wide Significance check box to enable enterprise style of configuration. In this mode, Contrail Networking ensures that every Layer 2 Service or VLAN ID in a fabric is unique, and that there is a 1:1 mapping between the VLAN ID (4K VLANs per fabric) and the Virtual Extensible LAN Network Identifier (VNI). In most cases, 4K bridge domains are enough any enterprise deployment. Hence, fabric-wide significance of a VLAN ID implies that any VLAN being provisioned in an EVPN VXLAN fabric maps to a VNI in a 1:1 ratio.

    Box is checked

    Underlay ASNs (eBGP)

    Provide a range of AS numbers to assign automatically to the underlay network. Each fabric device consumes one AS number. Ensure the range specified is large enough for the initial fabric size as well as any expected growth in fabric devices if the data center is expanded.

    • ASN From: Starting autonomous system number

    • ASN To: Ending autonomous system number


    Management subnets

    Addresses for your management subnet

    • CIDR: IP address and prefix length of the management subnet

    • Gateway: Default gateway for the management subnet

    • CIDR:

    • Gateway:

    Fabric subnets (CIDR)

    IP address and prefix length of the subnets you assign for the physical interfaces that connect the fabric devices to each other

    Loopback subnets (CIDR)

    IP address and prefix length of the subnets you assign for the loopback interfaces on your fabric devices

  5. Click Next. The device discovery process begins.

    The device discovery process discovers devices, physical interfaces, and logical interfaces. Expect this process to take 10 minutes or more to complete.

  6. When the device discovery process is complete, click Next to begin assigning roles to your onboarded fabric devices.

Assigning Roles to Devices

After the new fabric devices are discovered, you need to assign the roles that the devices will perform in the fabric. Assigning roles to devices to tailors the data center design and determines whether there is distributed or centralized routing.

To assign device roles:

  1. Put a check in the box next to the device or devices for which you want to assign roles.

    See Device Roles for information about configuring roles.

Applying the Role-Based Configurations to the New Fabric Devices

After you have assigned roles to the fabric devices, it is time to generate role-based configurations and push them to the devices. The autoconfigure process handles this task and simplifies the process of configuring the fabric devices.

To autoconfigure the fabric devices with their role-based configurations:

  1. Click Autoconfigure.
  2. Monitor the status of the autoconfiguration process. The Logs section of the screen and the Autoconfigure progress status bar display the progress of this process.
  3. The autoconfiguration process completes when the device configurations are pushed to each fabric device based on their role.

    When the Autoconfigure progress bar turns green and Job execution completed successfully appears in the Logs section (as shown below), you’ll know that the process is done.

  4. On the resulting screen, you can view the completed status of the new fabric. This includes the subnets for the fabric devices, loopback interfaces, and management network; along with the device roles and interfaces. To navigate to this page manually, go to Infrastructure > Fabrics > Fabric Name.