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How does failover of controllers work?

Question asked by SA Vault on Feb 12, 2014
Latest reply on Dec 20, 2015 by Vlad Valeriu Velciu

Hi there I have a 1Gb standard network configuration with eth1 & 2 management only and eth3-6 data only.

 

Each management port and data port on each controller are plugged into a separate switches as documented in the Nimble networking best practices:

 

 

 

I was wondering what triggers a failover of the controller?

 

There's a few scenarios I'm considering:

 

  • If S1 fails eth1, eth3 and eth 5 lose connections however we still have connections to eth 2, eth4 and eth6 so I guess no failover occurs as we still have connectivity from the controller but in a degraded state? and the same if S2 fails but with eth 2, 4 and 6?

 

If an individual port either on the switch or controller failed then what would happen?

 

  • in the case of the management network does failover rely on the availability of the group management IP address which 'floats' between the 2 management ports and if that becomes unavailable then failover occurs?
  • In the case of the data network, if one or more ports are unavailable on a controller then what happens?

 

I am not in a position to test failover scenarios at present but would like to know the theory behind failover.

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