Switching

I am trying to clarify my understanding on what if both the Master and backup member were to fail in a preprovisioned virtual chassis. my config is like this, i.e member 0 and 1 are REs for the VC ,member 2 is not pre-defined as linecard.

root# show virtual-chassis 
preprovisioned;
no-split-detection;
member 0 {
    role routing-engine;
    serial-number GD0215350xxx;
}
member 1 {
    role routing-engine;
    serial-number GA0215341xxx;
}
member 2 {
    serial-number GD0215350xxx;
}

{linecard:2}[edit]

When i bring down both master and backup members , member 2 would not transition into Master role and stay as LC.

root# run show virtual-chassis status    

Preprovisioned Virtual Chassis
Virtual Chassis ID: bc33.eea3.d4de
Virtual Chassis Mode: Enabled
                                           Mstr           Mixed Neighbor List
Member ID  Status   Serial No    Model     prio  Role      Mode ID  Interface
0 (FPC 0)  NotPrsnt GD0215350xxx ex3300-24t
1 (FPC 1)  NotPrsnt GA0215341xxx ex3300-48t
2 (FPC 2)  Prsnt    GD0215350xxx ex3300-24t   0  Linecard*   NA

{linecard:2}[edit]

in the above condition it is a complete disaster , as there is no switching at all.

Is it possible to configure the VC such that when both master and backup members fail , the Linecard can transition into Master role.If yes is it possible in the pre-provisioned mode OR only in non-provisioned mode ?

i have tried disabling split , but no change

set virtual-chassis no-split-detection

Thanks

This is the expected behavior on pre-provisioned mode. You can have only two REs. If both fails, the VC will stop forwarding packets.

It is expected that once the master fails, you will recover it as soon as possible to avoid double RE failure.

What you want to achieve is only possible in non-provisioned.

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If this worked for you please flag my post as an "Accepted Solution" so others can benefit. A kudo would be cool if you think I earned it.

Thanks for the prompt reply

Additionally you need to have 50%+1 of the switches still in the VC in order for the VC to stay alive.

I've been trying the same case but in non-provisioned mode ,  its a 3 member VC setup . The linecard never elevetates its role when the master and backup fail . I'm not sure if it should as i cant find any explanation from juniper regarding this specific scanerio but according to "50%+1 of the switches " i'll need to have a minimum of 5 memebers for the linecard to become a master! 

Can this be confirmed or am i missing something.

Have you set no-split-detect?  edit virtual-chassis no-split-detection

http://www.juniper.net/documentation/en_US/junos14.2/topics/concept/virtual-chassis-mx-series-split-detection.html

Since you now have a 1 member VC, it no longer operates like a VC, so I believe the results you are seeing are expected.  Please note that most redudnancy schemes, such as VC, are not specifically design for double or triple fault scenerios. Double/triple faults may recover, but are generally never quarenteed.

no-split detection is configured.  I managed to get the scanerio working but it was not related to VC configiration, my scanerio consists on 3 member VC connected through LACP to a cisco catalyst 4510r+e ,  i reversed the port modes for juniper to be the active and cicso to be the passive and evertyhing is working fine now!

Just to be sure i reverted the changes and i again end up with loss of connectivty to my juniper stack.

Thanks