Re: Split Brain recovery with haproxy/keepalived setup

I think in the event of both nodes being in a master state the node with a lower priority will move to backup state upon seeing the higher priority advertisement. However, in my experience you may still end up with some real servers on the network having the mac address for the lower priority node (now in backup state) in their arp tables. This is because the master doesn't re-send gratuitous arp upon the lower priority node transitioning from master to backup state.

-T

 the advert from a node with a higher priority

On Dec 27, 2013, at 1:26 AM, T. A. Smooth wrote:

> Once two keepalived systems enter a split brain state, is it expected behavior they can get out of it?
> 
> Looking at the code it seems they should be able to once they can see each others advertisements again. Even if they match priority it seems they check source IP next
> in vrrp.c
> 
> vrrp_state_master_rx(vrrp_t * vrrp, char *buf, int buflen)
> {
> ##<snip>##
> 	} else if (vrrp->family == AF_INET) {
> 		if (hd->priority > vrrp->effective_priority ||
> 		    (hd->priority == vrrp->effective_priority &&
> 		     ntohl(saddr) > ntohl(VRRP_PKT_SADDR(vrrp)))) {
> 			log_message(LOG_INFO, "VRRP_Instance(%s) Received higher prio advert"
> 					    , vrrp->iname);
> 			if (proto == IPPROTO_IPSEC_AH) {
> 				ah = (ipsec_ah_t *) (buf + sizeof(struct iphdr));
> 				log_message(LOG_INFO, "VRRP_Instance(%s) IPSEC-AH : Syncing seq_num"
> 						      " - Decrement seq"
> 						    , vrrp->iname);
> 				vrrp->ipsecah_counter->seq_number = ntohl(ah->seq_number) - 1;
> 				vrrp->ipsecah_counter->cycle = 0;
> 			}
> 			vrrp->ms_down_timer = 3 * vrrp->adver_int + VRRP_TIMER_SKEW(vrrp);
> 			vrrp->wantstate = VRRP_STATE_BACK;
> 			vrrp->state = VRRP_STATE_BACK;
> 			return 1;
> 		}
> 	}
> 
> Thoughts? Or is there a different line of code execution if there are two Master?
> 
> -tp-
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