Which two statements are true regarding NSX High Availability? (Choose two.)
A.
NSX HA is configured as Active-Active.
B.
NSX HA is configured as Active-Standby.
C.
If an Active node fails, there is no service interruption during failover.
D.
If an Active node fails, there is a 15 second service interruption during failover.
B, C
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Agreed Correct B,C are correct.
The following are some important design and deployment considerations relative to the behavior of this HA model:
• The Standby NSX Edge leverages the expiration of a specific “Declare Dead Time” timer to detect the failure of its
Active peer. This timer is configured by default to 15 seconds and can be tuned down to a minimum value of 6
seconds (via UI or API call) and it is the main factor influencing the traffic outage experienced with this HA model.
• Once the Standby gets activated, it starts all the services that were running on the failed Edge (routing, firewalling,
etc.). While the services are restarting, traffic can still be routed leveraging the information in the NSX Edge
forwarding table that was kept in synch between the Active and the Standby Edge units. The same applies to the
other logical services, since the state is synchronized and available also for FW, LB, NAT, etc.
Note: for the LB service only the persistence state is synchronized between the Active and the Standby units.
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What am I missing here? Shouldn’t the answer be B,D?
If there is a 6-15 delay before the Standby realizes the Active is down, won’t traffic still be going to a device that is not there during that window? Seems to me like that would cause a service interruption.
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Answer should be B and D
https://pubs.vmware.com/NSX-6/index.jsp?topic=%2Fcom.vmware.nsx.admin.doc%2FGUID-6C4F0C33-C6DD-432B-AA91-10AD6B449125.html
services need to re-establish TCP connection with NSX Edge, so service is disrupted for a short while
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Answer B and C, but I agree, they ask the question in a way that more options are posible.
The documents says:
If a heartbeat is not received from the primary appliance within the specified time (default value is 15 seconds), the primary appliance is declared dead. The standby appliance moves to the active state, takes over the interface configuration of the primary appliance, and starts the NSX Edge services that were running on the primary appliance. When the switch over takes place, a system event is displayed in the System Events tab of Settings & Reports. Load Balancer and VPN services need to re-establish TCP connection with NSX Edge, so service is disrupted for a short while. Logical switch connections and firewall sessions are synched between the primary and standby appliances, so there is no service disruption during switch over.
So for routing and firewall sessions there is no disruption and for VPN and loadbalacing there is a short disruption.
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I believe the answer here is B, D.
If the secondary does not take over until 15 secs have passed of no heartbeats. Then regardless of whether state information is maintained and some services are resumed as soon as the secondary takes over, – there has been a 15 second gap. Therefore there is a 15 second service interruption. Period.
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This is a tricky one and too open-ended. While there are now switch or FW disruptions, I suppose those are the most important services which need to remain up, hence B and C.
A question I’d ask VMware is what service(s) are they referring to in this question?
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I’d go B and C as D is a field that can be changed (can be as low as 6).
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Good point ! 🙂
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