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Configuring Mastership of a Virtual Chassis

 
Note

This topic applies to all QFX Virtual Chassis and all EX Series Virtual Chassis except EX8200 Virtual Chassis.

A Virtual Chassis configuration has two Routing Engines—one is the switch in the master Routing Engine role and the other is the switch in the backup Routing Engine role. The remaining members operate in the linecard role. You can designate the role (master, backup, or linecard) that a member switch performs within any Virtual Chassis whether or not you are using a preprovisioned configuration. For details on which switches in a mixed Virtual Chassis we recommend or require you to configure into the master or backup Routing Engine role, see Understanding Mixed EX Series and QFX Series Virtual Chassis.

Note

We recommend that you always use commit synchronize rather than commit to save configuration changes for a Virtual Chassis to ensure that the changes are saved on both Routing Engines.

Configuring Mastership Using a Preprovisioned Configuration File

To configure mastership using a preprovisioned configuration:

  1. Note the serial numbers of the switches that you want to function as the master and backup Routing Engines.Note

    Serial number values are case-sensitive.

  2. Power on only the switch that you want to function as the master Routing Engine.
  3. Edit the configuration to specify the preprovisioned configuration mode:
    [edit virtual-chassis]

    user@switch# set preprovisioned

  4. Specify the serial numbers of the member switches that you want to function as master and backup, specifying their role as routing-engine:
    [edit]


    user@switch# set virtual-chassis member 0 serial-number abc123 role routing-engine


    user@switch# set virtual-chassis member 1 serial-number def456 role routing-engine


    Note

    You cannot directly modify the mastership priority value when you are preprovisioning a Virtual Chassis. The mastership priority values are generated automatically and controlled by the role that is assigned to the member switch in the configuration file. The two members assigned the routing-engine role are assigned the same mastership priority value, 128. However, the member that was powered on first gets priority in the master election algorithm. See Understanding How the Master in a Virtual Chassis Is Elected. Only two members can be configured with the routing-engine role.

  5. Specify the serial numbers of any other member switches you are including in the Virtual Chassis configuration. You can also explicitly configure their role as line-card.

Configuring Mastership Using a Configuration File That Is Not Preprovisioned

To configure mastership of the Virtual Chassis through a configuration that is not preprovisioned:

  1. Power on only the switch that you want to function as the master Routing Engine.
  2. Configure the highest possible mastership priority value (255) for the member that you want to function as the master Routing Engine:
    [edit virtual-chassis]

    user@switch# set member 0 mastership-priority 255
  3. Configure the same mastership priority value (continue to edit the Virtual Chassis configuration on the master) for the member that you want to be the backup Routing Engine:
    [edit virtual-chassis]

    user@switch# set member 1 mastership-priority 255
    Note

    You should assign the same (highest) mastership priority value to both the master and backup Routing Engine members for reliable graceful Routing Engine switchover (GRES) operation. This and the other mastership election considerations also help keep mastership from switching back and forth rapidly between the two members under failover conditions.

  4. Use the default mastership priority value (128) for the remaining member switches or configure the mastership priority to a value that is lower than the value specified for members acting in the master and backup Routing Engine roles.