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Creating Virtual Chassis with EX3400's

  • 1.  Creating Virtual Chassis with EX3400's

    Posted 06-13-2017 08:16

    Hi All,


    I'm very new to Juniper and need assistance trying to create a VC with EX3400's.  I've searched the Knowlege Base and it seems that the setup is version specific and model specific sometimes.  I've had trouble finding all the data I need and I'd be appreciative if someone could give me more info.  I'm coming from an Enterasys shop where no commands are necessary in the CLI beforehand, just power down, attach cables, and power up.  I'm finding the Juniper switches much more favorable.... except for this one thing!


    I have used the following in Member 0 of a closet with 5 switches that I want to stack together.

    set virtual-chassis member 0 mastership-priority 255

    set virtual-chassis member 1 mastership-priority 255


    When I attempted this, upon powering up Member 1, Member 0 lost connectivity and the only lights on the front were SYS and SPD.  Member 1 appeared to become the backup as it had the SYS LED, SPD, and flashing green MST, eventually going solid green.   Consoling in to Member 0 showed it to be a linecard and consoling in to Member 1 showed it to be "Master 1" and running 

    show virtual-chassis

    Returned that is was the only switch in the VC.  It did not see member 0 at all.


    Previous to that attempt, I used the pre-provisioned method and listed the SN of all 5 switches and making member 0 and member 1 be routing-engines and the remaining 3 as linecards.  This also resulted in disaster.  I powered on Member 0 and all was fine, upon powering on the remaining switches (with cables already connected) no switch (including member 0 now) had any lights except SYS and SPD.  None were a Master, all showed as being a linecard.

    As downtime was limited, in both instances, I restored to factory default and configured each individually with trunks between.  


    Am I missing a command?  Do all switches need to be set at factory-defaults with no configuration, except for Member 0, of course?  Do switches being added need to powered on or off when cables are connected.  All switches are on the same firmware version (15.1X53-D51).  Four are EX3400-48 and one is an EX3400-24.  I used a ring topology using the VC ports on the rear of the device.


    There is a lot of documentation that specifically lists the 4200, 4500, 8200, etc. but very little that specifically names the EX3400.  Is it done differently on the 3400?  Any help would be appreciated.

  • 2.  RE: Creating Virtual Chassis with EX3400's

  • 3.  RE: Creating Virtual Chassis with EX3400's

    Posted 06-14-2017 03:16

    I suspect based on your description that perhaps not all of the setup for your pre provision VC was removed before you did this new setup leading to the inconsistent results.


    The other item to be aware of is you should set the priority to be lower on member 1 assuming you want to keep mastership on member 0 unless there is a failure.  By setting them the same you no longer fully control the election process.


    At this point, I would suggest reseting to factory default to start the process again.  

    request system zeroize


    If that is not feasible, you are probably best to open a JTAC offical ticket so an engineer and do a deep dive on the configs and guide you to a less service affecting transition.

  • 4.  RE: Creating Virtual Chassis with EX3400's

    Posted 06-17-2017 19:45



    This is what I would suggest lets say we are needing a 4 member VC


    1) Zeroize/FD all the 4 members.

    2) Take one switch which you wan to be master, configure this with preprovisioned.

    3) Make sure all devices in same code.

    4) Add them one by one to the VC.


    This would help.



  • 5.  RE: Creating Virtual Chassis with EX3400's

    Posted 06-19-2017 09:39

    Other than the Master, do the remaining switches to be added to the VC need any config, assuming they were zeroized and immediately powered down?

    Is it best practice to power on member switches and THEN cable them?  Or cable and then power on?



    Sorry if these are irritating questions - I'm a noob on Juniper. 

  • 6.  RE: Creating Virtual Chassis with EX3400's

    Posted 06-19-2017 15:23

    Confirm the same version of Junos as the master is installed

    Connect the switches via the VCP cable

    Power the switch on and it will automatically add to the VC


    I usually do this one switch at a time.