HA Primary

[rzg62s_BPC]

Why is it when I have a HA pair with an identical link failure on both devices (same monitors configured), the device with the higher 'device priority' value (least preferred) becomes the Primary device?

When a pair of devices has the same failure the device with the lowest priority (most preferred) should be the primary.

It seems to end up on the least preferred device after going through the flap count. The devices do not seem to be taking into account any sort of election value to determine if they should fail over.

[nbilly]

Hello,

Priorities in election process will trigger a failover only if preemption is enabled.

The active node will spontaneaously request the passive to become active after preemption hold timer expired.

Regards

-Nicolas

[rzg62s_BPC]

Sorry, I forgot to list that Pre-emption is configured and certainly does work when inflicting individual failures on the devices in any sequence, the preferred device will go to active unless there is an identical failure condition on the devices.

Passive link state is also set to auto.

I have observed this behaviour in at least a dozen installations. I'm currently installing 13 pairs of HA devices (active-active and active-passive) in various projects and see the same behaviour.

OK, just finished a little experiment:

1. On a HA pair that have 4 interfaces configured on each device

2. Two interfaces (same interfaces) on each device are not connected

3. On the preferred device (lowest value) I have configured only 3 interfaces in a link monitor group (left out on disconnected interface)

4. On the least preferred device (highest value) I have configured all 4 interfaces in a link monitor group

5. Suspended the least preferred device (preferred became active)

6. Made least preferred device functional (quickly goes to passive)

7. One minute later the least preferred device becomes active and the preferred device is set to non-functional.

Clearly there is much more detailed information then what is contained in the administration manual to get a desired failover function is there a detailed document that might give me detailed configurations and scenarios?

I need to go back to all my installs and ensure each interface monitor is in its own link group for a start.....

[SCoupland]

That sounds like expected behaviour. The most preferred device hits the maximum number of flaps and goes non-functional as a result. The least preferred device then stays active as it now ignores the link failure condition due to the device not knowing whether the HA will be honoured as the most preferred device is not participating in the HA due to being in a non-functional state.