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I am trying to understand if there is a relation between garp_master_delay and advert_int. In all the configurations I saw, advert_int was less than garp_master_delay.

  • Is there any reason for this?
  • Are those independent of each other or is there any ordering requirement between the two?

VRRP RFC does not seem to mention anything on this.

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They aren't really related, per se - the advert_int controls the interval between advertisements in normal operation, whereas the garp_master_delay controls how long after taking master state a node should sent gratuitous ARP (to notify devices that it now controls those IPs at a new MAC address to override their ARP caches). You'd tune the two for different reasons.

  • Thanks for the explanation. Shouldn't it make more sense for garp_master_delay to be 1s or less? That way all devices will know about the master sooner. Why does it default to 5s, which looks like a larger value? – Abhishek Chanda Dec 17 '14 at 19:30
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    @AbhishekChanda My guess is the rather conservative default is for compatibility reasons. In a case where you're failing back and forth rapidly (usually due to communication problems between the VRRP nodes) you don't want both nodes spewing GARP constantly - I've seen network devices start completely ignoring ARP from an offending IP address in those kinds of cases. – Shane Madden Dec 17 '14 at 20:29
  • This exact thing happened to us. Primary failed, secondary took over, primary came back up really quickly and we had conflicting arp tables everywhere. It took a few minutes to diagnose which sucked... – Clint Oct 16 '17 at 20:59

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