Manage a Virtual Chassis Using Mist (Add, Delete, Replace, and Modify Members)
Follow these steps to manage the members of a Virtual Chassis.
You can use the Modify Virtual Chassis option on the switch details page to manage your Virtual Chassis. The operations you can perform include renumbering and replacing the Virtual Chassis members and adding new members to a Virtual Chassis.
The Modify Virtual Chassis workflow leverages the Junos preprovisioning method which configures the role and serial number of all members in a Virtual Chassis.
The preprovisioned configuration specifies the chassis serial number, member ID, and role for both member switches in the Virtual Chassis. When a new member router joins the Virtual Chassis, Junos compares its serial number against the values specified in the preprovisioned configuration. Preprovisioning prevents any accidental role assignment to a Routing Engine, or any accidental addition of a new member to the Virtual Chassis. Role assignments, member ID assignments, and additions or deletions of members in Virtual Chassis are under the control of a preprovisioned configuration.

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The Modify Virtual Chassis option is available:
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To Super Users or Network Admins.
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For switches that have their configuration managed by Mist.
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This workflow applies to all the EX Series and QFX Series platforms that support Virtual Chassis.
- To delete a member whose MAC address is used as the Virtual Chassis device ID, trash and replace it with an existing member in the Virtual Chassis. To verify if any Virtual Chassis member is used as the device identifier, look for the device ID on the switch details page (Virtual Chassis page) or on the switch list.
- The Add Switch dropdown only shows the switches that:
- Are part of the same site. Models with dedicated Virtual Chassis ports can be in connected or disconnected state. However, to modify the EX2300, EX4650, or QFX5120 Virtual Chassis, the members should be in the connected state as these switches don’t have dedicated Virtual Chassis ports.
- Have configuration management enabled in Mist.
- Are not currently part of the same or another Virtual Chassis.
- Are of the same model family. For example, an EX4100-F switch can be part of a Virtual Chassis with an EX4100-48MP switch.
- The Modify Virtual Chassis button is disabled when the Configuration Management option is disabled for the switch.
- When a Virtual Chassis configuration is in progress, you cannot make any changes inside the Modify Virtual Chassis page.
Prerequisites
Before your perform any modification to a Virtual Chassis, you must remove all the
additional CLI commands specific to Virtual Chassis (the
virtual-chassis
commands) from the associated device or site
template. The additional CLI commands take precedence over other types of
configurations. If a Virtual Chassis configuration is detected under the Additional
CLI Commands section, you cannot make any changes using the Modify
Virtual Chassis option. When you attempt to modify a Virtual
Chassis, the Mist dashboard displays a message to indicate that the Additional CLI
commands (if present) need to be removed and saved.
Replace a Virtual Chassis Member
Instructions in this topic apply to any Virtual Chassis device that has a device ID starting with '0200', as shown in the image below. If the Virtual Chassis uses a member MAC address as its device identifier, you must follow the instructions in Replace a Member Whose MAC Address is Used as Virtual Chassis Device ID to avoid any connectivity disruptions during the process. You can find the device ID on the switch details page (Virtual Chassis page).

Replacing a Virtual Chassis member switch involves deleting the old member and adding a new member. Before replacing a member switch, you must ensure that:
- The new switch is of the same model family as the other members in the Virtual Chassis.
- The new switch is connected to the Virtual Chassis.
- The new switch is assigned to the same site as the other members in the Virtual Chassis.
To replace a Virtual Chassis member that has a device ID starting with '0200':
Replace a Member Whose MAC Address is Used as Virtual Chassis Device ID
Instructions in this topic apply to any Virtual Chassis device that uses a member MAC address as its device identifier, as shown in the image below. If the Virtual Chassis that has a device ID starting with 0200, you must follow the instructions in Replace a Virtual Chassis Member to replace its members. You can find the device ID on the switch details page (Virtual Chassis page).

If a Virtual Chassis uses the MAC address of a member (typically the FPC0) as the device identifier, you cannot replace that member in a single operation as it is used to communicate to the Mist cloud. You need to carry out the replacement in a 2-step process that includes adding the new replacement switch and then removing the switch to be replaced. In such cases, you should carry out the member replacement operation in a maintenance window as this operation can impact the traffic to the clients connected.
Before replacing a member switch, you must ensure that:
- The new switch is of the same model family as the other members in the Virtual Chassis.
- The new switch is connected to the Virtual Chassis.
- The new switch is assigned to the same site as the other members in the Virtual Chassis.
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The Virtual Chassis is pre-provisioned. For a 2-member VC, the split and merge feature is disabled by default (no-split-detection) if the Virtual Chassis is provisioned by the cloud.
To replace a member (FPC0, for example) whose MAC address is used as the Virtual Chassis device ID:
Renumber the Virtual Chassis Members
If you prefer to see the Virtual Chassis members on the Mist portal in the same order as they are physically stacked, you need to reorder the switches (after they are powered on and connected to Virtual Chassis) using the Modify Virtual Chassis option.
You can modify the member switches’ order on the Mist portal by renumbering the members. On the Modify Virtual Chassis window, accessible from the switch details page, you can move around the port panel of a switch to change the order of the member. The order is incremental. The first entry is member 0, the second is member 1, and so on. You are required to specify the FPC0.
To renumber the switches in a preprovisioned Virtual Chassis:
Reassign Virtual Chassis Member Roles
A Virtual Chassis configuration in a Juniper Mist™ network has two switches in the Routing Engine role - one in the primary Routing Engine role, and the other in the backup Routing Engine role. The remaining member switches operate in the linecard role. You can change the role of a switch from primary to backup or backup to linecard or linecard to primary.
To change the role of Virtual Chassis members:
You will see the updated status about the role change on the switches page on the Mist portal. The role change will take some time (approximately 15 minutes) to appear on the Mist portal. You can see a banner message at the top after every change that you make, as shown below:

Delete Virtual Chassis Members
You can delete the member switches from the Virtual Chassis, by clicking the delete (trash) icon on the Modify Virtual Chassis window. Before deleting any member switch, you must ensure that the switch to be removed is disconnected from the Virtual Chassis. If the switch is connected, power it off or remove the VCP connection from it.
To delete a member switch from Virtual Chassis:
Add a Member Switch to a Virtual Chassis
You can add one or more member switches to a Virtual Chassis from the Modify Virtual Chassis window. Before adding a new member switch to a Virtual Chassis, ensure the following:
- The new switch is of the same model family as the other members in the Virtual Chassis.
- The new switch is connected to the network (applicable to EX2300, EX4650, and QFX5120).
- The new switch is assigned to the same site as the other members in the Virtual Chassis.
Juniper Mist automatically upgrades a Virtual Chassis linecard member if it is running a Junos version different from that of the primary member. The linecard member will be upgraded to the same version as the primary member if the following conditions are met:
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The switch must form a Virtual Chassis with three or more members—that is, a primary, a backup, and a linecard member.
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The Junos version on the linecard member is different from that on the primary member.
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The linecard member must be in Inactive state.
Note that a linecard member will be upgraded only if it is inactive and running a clearly different Junos version. Minor differences, such as different spin numbers, will not trigger an upgrade.
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Only the Junos versions listed on the Mist portal are available for upgrade.
To add a new member switch to the Virtual Chassis: