Reasons/conditions for CARP state change
Could someone please point me at a doc or confirm all the situations/conditions/reasons for a CARP state change (i.e. Master -> Backup or Backup -> Master)
What I have so far are:
- Physical port down
- Not receiving advertisement from peer (usually due to a layer 2 issue/misconfig)
- Receiving an "unexpected" advertisement with the same VHID (e.g. from other devices running vrrp on the same physical network)
- MAC address conflict (probably relating to above)
- Manual change of advskew
- Platform specific issues when using hypervisors/VMs
Have I missed anything please? Thanks.
The hypervisor/VM issue isn't really one of it's own, it's just a variation of one of the others (likely the second point in your list)
The only one I don't see there is entering maintenance mode, which isn't exactly a manual change of advskew since the user isn't editing advskew directly, but it is similar as the system automatically sets an advskew of 254 when in maintenance mode.
And "MAC address conflict" isn't really the root cause of a CARP issue. A VHID conflict would be. Two systems with CARP VIPs on the same L2 using the same VHID will technically have the same MAC, but it's not the MAC that's the problem, it's the conflicting VHID advertisements.
Thanks for that clarification @jimp. It helps.