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Adding a New Switch to an Existing EX4650 or QFX Series Virtual Chassis

Note:

If the Virtual Chassis is managed through Juniper Mist, see the following topic for instructions to add a member switch: Add a Member Switch to a Virtual Chassis.

Use this procedure to add a new switch to an EX4650 or a QFX Series Virtual Chassis.

To add a switch to a Virtual Chassis Fabric (VCF), see Adding a Device to a Virtual Chassis Fabric.

Add a New Switch to an EX4650 or QFX Series Virtual Chassis

You can use this procedure to add a switch in a supported combination to an existing EX4650 or QFX Series Virtual Chassis. A Virtual Chassis is a supported combination of switches interconnected using Virtual Chassis ports (VCPs). EX4650, QFX5120 and QFX5200 switches can be members of a non-mixed Virtual Chassis only (all members must be the same type of switch). QFX series switches that can be members of a mixed or non-mixed Virtual Chassis include QFX3500, QFX3600, QFX5100, and QFX5110 switches.,. EX4300 switches can also be members of a mixed QFX Series Virtual Chassis with QFX3500, QFX3600, and QFX5100 switches. See Understanding Mixed EX Series and QFX Series Virtual Chassis for details on the types and combinations of switches that can make up a mixed QFX Series Virtual Chassis.

Note:

EX4300 multigigabit model (EX4300-48MP) switches are not supported in a mixed Virtual Chassis with QFX Series switches.

Before you begin, make sure you have:

  • Mounted the new switch in a rack.

  • Enabled automatic software updates on the Virtual Chassis. See Configuring Automatic Software Update on Virtual Chassis Member Switches.

    CAUTION:

    When adding a QFX5100 switch installed with a “-qfx-5-” Junos OS image to a QFX5110 Virtual Chassis, you must first upgrade the QFX5100 switch to run a “-qfx-5e-” Junos OS image.before this step in the procedure. The automatic software update feature cannot automatically update a QFX5100 switch running a “-qfx-5-” Junos OS image to a “-qfx-5e-” image. See Upgrading a QFX5100 Switch with a USB Device to Join a QFX5110 Virtual Chassis or Virtual Chassis Fabric

  • Determined which ports you will use as Virtual Chassis ports on the new switch, and the member ports in the existing Virtual Chassis to which you will interconnect the new switch.

  • If you are expanding a preprovisioned configuration:

    • Made a note of the serial number (the number is on the back of the switch). You’ll need to edit the Virtual Chassis configuration to include the serial number of the new member switch.

      Note:

      Serial number values are case-sensitive.

    • Edited the existing Virtual Chassis configuration to include the serial number of the new member switch. The Virtual Chassis applies the parameters in the primary’s configuration file to the new switch after it has been interconnected with an existing member switch.

    • (If you are using the autoprovisioning feature to add a member switch to an existing preprovisioned Virtual Chassis) Confirmed that the member ports in the Virtual Chassis to which you will interconnect the new switch are not already configured as VCPs. One condition for automatic VCP conversion is that the ports on both sides of the new link must not already be configured as VCPs. See Automatic Virtual Chassis Port (VCP) Conversion for details.

  • (Optional) Configured Ethernet interfaces on different member switches into the same LAG. See Configuring Link Aggregation.

    An active member switch might temporarily go down before coming back up as part of this procedure. If you configure the Virtual Chassis members so that traffic is load-balanced across member switches using a LAG, you can alleviate traffic loss during this procedure.

To add a new member switch to an existing EX4650 or QFX Series Virtual Chassis configuration:

  1. If you previously configured the new member switch, we recommend you revert that switch’s configuration to the factory defaults before interconnecting it into the Virtual Chassis. See Reverting to the Default Factory Configuration.
  2. (Recommended for a QFX5100 Virtual Chassis under certain conditions) When you add or replace a QFX5100-24Q switch that is configured in the Routing Engine role in a QFX5100 Virtual Chassis, if the new switch has two EX4600-EM-8F expansion modules, we recommend that you set the primary role priorities on the routing engine members and the new switch to prevent a primary-role switchover to the new switch until after the new switch is completely initialized in the Virtual Chassis.

    Before interconnecting the new switch into the Virtual Chassis in this case, see Add or Replace a QFX5100-24Q Switch with Two Expansion Modules in a QFX5100 Virtual Chassis for details on why, when, and how you should do this step.

    Note:

    You might need to do this even if the new switch has the default factory configuration.

  3. (Required for a mixed Virtual Chassis only) Set the new switch into mixed mode and reboot the switch to complete the configuration:
    Note:

    You do not need to configure your Virtual Chassis into mixed mode if the Virtual Chassis is composed of only QFX3500 and QFX3600 switches or only QFX5110 and QFX5100 switches (which are considered non-mixed Virtual Chassis).

    If you are adding a switch that converts a non-mixed Virtual Chassis into a mixed Virtual Chassis, you must also log onto the Virtual Chassis and enter the request virtual-chassis mode mixed all-members reboot command either before or after interconnecting the new switch into your Virtual Chassis. This step makes sure all switches in the Virtual Chassis can communicate with the new mixed-mode member switch.

  4. Interconnect the new switch to one member of the existing Virtual Chassis using an interface that can be configured into a VCP. See Virtual Chassis Port Options for details on ports you can use as VCPs on different switches.

    Connect only one interface on the new switch to a VCP on a member switch in the existing Virtual Chassis at this point of the procedure.

  5. Set the interconnecting ports for the new member switch as Virtual Chassis Ports (VCPs) on the new member switch and the existing Virtual Chassis member switch where you connected the new switch, if needed:
    Note:

    Include the local option in this command if you want to make sure the command applies only to that port locally on the switch where you’re running the command.

    You do not need to perform this step in a preprovisioned Virtual Chassis if you set up the right conditions to use the autoprovisioning feature (see Automatic Virtual Chassis Port (VCP) Conversion). After the new switch is provisioned and cabled into the Virtual Chassis, the interconnecting links automatically convert into VCP links. You do not need to manually set the ports on either side of the links as VCPs.

  6. Confirm that the new member switch is now included within the Virtual Chassis configuration by entering the show virtual-chassis command on a Virtual Chassis console or management port. You should see the new member switch listed in the output with Status displayed as Prsnt.
  7. Cable the next port into the Virtual Chassis. Refer to Steps 4 through 6 in this procedure.
    CAUTION:

    If you immediately cable both VCPs on the new switch into the existing Virtual Chassis at the same time, a member switch that was already part of the Virtual Chassis might become non-operational for several seconds. The Virtual Chassis drops network traffic to this switch during the downtime.

    The member switch returns to the normal operational state with no user intervention, and normal operation of the Virtual Chassis resumes after this downtime.

  8. Split detection is enabled in a Virtual Chassis by default. We recommend configuring the no-split-detection option to disable it in a Virtual Chassis that has only two members. We very strongly recommend keeping it enabled in a Virtual Chassis that has more than two members. See Understanding Split and Merge in a Virtual Chassis for details.

    If your Virtual Chassis had only two members with no-split-detection configured, now that you’ve added another member switch in this procedure, enable split detection again (in other words, remove the no-split-detection setting):

  9. If you need to customize your Virtual Chassis configuration further, see Configuring an EX4650 or a QFX Series Virtual Chassis or Removing or Replacing a Member Switch of a Virtual Chassis Configuration.

See Also

Add or Replace a QFX5100-24Q Switch with Two Expansion Modules in a QFX5100 Virtual Chassis

A QFX5100-24Q switch installed with two EX4600-EM-8F expansion modules needs more time to check and initialize all its interfaces than a switch with one or no expansion modules. If you add a new switch or replace a member switch in an QFX5100 Virtual Chassis, when you connect and power on the new switch, the Virtual Chassis detects the new switch and reconfigures the Virtual Chassis to include it.

During that time, the Virtual Chassis might reassign primary role to the new switch before it is fully initialized and ready to take the primary Routing Engine role. This might happen if the new switch

  • is a QFX5100 switch with two expansion modules,

  • is configured in the Routing Engine role,

  • has a system MAC address lower than the other member switches in the Routing Engine role, and

  • has the same primary-role priority as the other member switches in the Routing Engine role.

See Understanding How the Primary in a Virtual Chassis Is Elected for more information on primary-role election.

The Virtual Chassis takes significantly longer to re-stabilize across a primary-role switchover during Virtual Chassis reconfiguration, which causes traffic loss. To avoid a primary-role switchover in this case, before cabling the new switch into the Virtual Chassis, you can reassign the new switch’s primary-role priority to be lower than the other Virtual Chassis member switches configured in the Routing Engine role.

For example, you have a QFX5100 Virtual Chassis with member 0 as the primary routing engine and member 1 as the backup routing engine. Both members have primary-role priority 255 in the current Virtual Chassis configuration, and you want to replace member 0 with a QFX5100-24Q switch that has two expansion modules.

  1. Remove member 0 according to the procedure in Remove a Member Switch and Make Its Member ID Available for Reassignment to a Different Switch.

    Member 1 assumes primary role of the Virtual Chassis.

  2. Reconfigure the primary-role priority of member 0 on the Virtual Chassis to a lower number than member 1 to make sure member 1 retains primary role while you replace member 0:
  3. Add the new member 0 into the Virtual Chassis using the procedure in Add a New Switch to an EX4650 or QFX Series Virtual Chassis, or continue with the steps in Remove a Member Switch, Replace It with a Different Switch, and Reapply the Old Configuration after removing the member you are replacing.
  4. After the new member switch is fully initialized and established as a member of the Virtual Chassis, you can restore the primary role priorities on member 0 so the Virtual Chassis switches primary role back to the new member 0:

See Configuring Primary Role of a Virtual Chassis for more details on changing primary role priorities.

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