Hi, The 'preempt delay' element means that it won't go active for xxx seconds _if_ there is a lower priority instance already visible. However - if the other instance is _not_ visible, then it goes active immediately.
In your case, I suspect there was a layer-2 adjacency issue (maybe an STP re-convergence) which meant that it couldn't see the hellos from the other (now active) unit and thus there was a double-active scenario. Then, after STP had converged your secondary unit saw higher priority (and active) hellos and thus immediately went into the backup role again. Leaving your primary unit to blackhole until it re-converged it's IGP. The resolution will depend on the rest of your infrastructure between the two units, maybe tune STP timers to be quicker than HSRP initial failures. Also, there is a keyword for 'reload' delay under preempt, which is separate to the one you are using, which maybe will also apply during a failover event? (config-if)#standby 0 preempt delay reload ? <0-3600> Number of seconds for reload delay Hope that helps! Robert Williams Custodian Data Centre Email: [email protected] http://www.CustodianDC.com -----Original Message----- From: cisco-nsp [mailto:[email protected]] On Behalf Of Randy Sent: 01 August 2014 21:16 To: [email protected] Subject: [c-nsp] HSRP failover/failback question I've got an HSRP setup between two 6500's. Today the primary active router's sup took a dump and failed over to the standby. The blip caused the standby router to take over the HSRP gateway on each VLAN as expected. However once the failover was complete on the primary router it *immediately* took over the GW's again. And of course, before it had a full routing table so there was several minutes of blackholing. I thought we'd be protected from this with the following config, but I guess not: PRIMARY ROUTER VLAN X: standby version 2 standby 0 ip x.x.x.x standby 0 priority 150 standby 0 preempt delay minimum 600 SECONDARY ROUTER VLAN X: standby version 2 standby 0 ip x.x.x.x standby 0 preempt delay minimum 600 What am I missing? Thanks! ~Randy _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
