Description

This article provides a step-by-step procedure for replacing a faulty SRX managed by Mist with a new RMA replacement.

Solution

Prerequisites:

  1. Zeroize the new device that will replace any SRX.
  2. Ensure that the device can reach the internet or can ping 8.8.8.8.
  3. Keep the new device onboarded (unassigned) on the MIST platform. Please refer to Link for the steps to adopt SRX.
  4. Verify that the JUNOS version of the new (unassigned) device is within the upgrade path of the target Junos version for the device. If it is not, a manual upgrade is recommended.
    For upgrade paths, please see https://supportportal.juniper.net/s/article/Junos-upgrade-paths-for-SRX-platforms 
  5. If the new (unassigned) device is an srx3xx and is below Junos 24.2 or lower and the target version is 24.4 or higher (or visa versa), a manual upgrade is required.
    Please see https://supportportal.juniper.net/s/article/Upgrading-the-srx3xx-branch-series-devices-to-Junos-24-4

Once the new SRX is onboarded as unassigned on the MIST platform, follow these steps to replace the SRX:

  1. Go to Organization > Inventory > WAN Edges > Select the Site from the UI.
  2. Click on the SRX.
  3. Once the WAN Edge Page is available, select Utilities > Replace WAN Edge.

4. Choose the SRX shown in the Replace window that you want to replace.

5. The MAC address of the unassigned SRX will be available in the drop-down list.


Please refer to [Mist-SRX] Replacing a node on a chassis cluster for the steps to replace the cluster on the MIST platform.

 

The device being replaced if still online, will still have the configuration after the process is completed.

Please consider that due to this, you will have 2 different devices with the same config and that could create problems in the network.

 

 

Additional notes if this is a cluster node replacement:

 

Before you begin, if you have preempt configured on the redundancy groups, deactivate those lines with additional CLI commands.

From the remote shell:

mist@node1> show configuration | display set | match preempt
set chassis cluster redundancy-group 1 preempt
set chassis cluster redundancy-group 1 preempt
set chassis cluster redundancy-group 1 preempt


In this example, we have preempt on three redundancy groups. So we will add the following to the additional CLI commands at the bottom.

deactivate chassis cluster redundancy-group 1 preempt
deactivate chassis cluster redundancy-group 2 preempt
deactivate chassis cluster redundancy-group 3 preempt


Save, and sync the configuration.


After the replacement is complete and the new SRX has rejoined the cluster in a healthy state, remove the above additional CLI commands, then save and re-sync.


Additional cluster notes:

  • This process will take about 30 minutes to an hour.
  • Make sure the replacement device is the exact same hardware.
  • Mist will automatically upgrade the replacement to the same Junos version as the other node.
  • Mist will then set the node to clustering and reboot it.
  • The new node will come online and then inherit the configuration from the existing node.


After the replacement is complete and the new node has joined the cluster in a healthy state, an additional re-sync of the Mist configuration is suggested. If you have already done this to re-enable preempt, this is not necessary.

 

Modification History

2024-05-12 : Article Created

2025-07-08 : Added additional notes for cluster node replacement

2025-07-21 : Clarified "similar" Junos version for upgrade/downgrade.