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An HP Comware switch is controlled by a team of HP VAN SDN Controllers. The controllers have these roles within the region that contains the switch.
Controller 1 = Master
Controller 2 = Primary slave
Controller 3 =Secondary slave
A failed network connection causes Controller 1 to lose contact with the switch. Controller 2 and Controller 3 can still reach all the controlled devices. Controller 1 is still up and has contact with other controllers and switches. How does the team handle this situation?
A. Controller 1, as master, contacts OpenFlow-enabled devices near the switch and attempts to repairthe connection.
B. Controller 2 becomes the master for this switch, although Controller 1 remains master for other switches.
C. Controller 1, as master, removes the switch from any active flows and sends updated flows to Controller 2 andController 3.
D. Controller 2 becomes the master for all switches in the region, and Controller 1 becomes the primary slave for the region.
Correct Answer: B
Explanation/Reference:
Explanation:
Device Owner Service triggers the failover operation in two cases:
*Device disconnect (the scenario here in this question): The Device Owner Service instance in a controller is notified of a communication failure with network device (s) through the Controller Service notifications. It instantly communicates with all Device Owner Service instances in the team to determine if the network device(s) in question are still connected to any of the backup (slave) controllers within the team. If that is the case, it elects one of the slaves to assume the master role over the affected network device(s).
The first slave will be chosen as master if it still has connectivity with the device(s), and the second slave will be chosen as master if neither the configured master or first slave have connectivity with the device(s).
*Controller failure: The Device Owner Service detects a controller failure in a team through notifications from the teaming subsystem. If Device Owner Service determines that the failed controller instance was a master for any devices within a region, it immediately elects an appropriate backup (slave) controller to assume the master role over the affected devices.
References:
http://h22208.www2.hpe.eom/eginfolib/networkingZdocs/sdn/sdnc2_6/5998-8472admin/content/s_curl-team-config.html#s_region-failover
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