critical FYI secondary in partner-down

perl-list perl-list at
Tue Aug 7 18:29:02 UTC 2012

what is your mclt set to? 

failover peer "dhcp" { 
address x.x.x.x ; 
port N ; 
peer address x.x.x.x ; 
peer port N ; 
mclt 990; 
split 128; 
max-response-delay 60; 
max-unacked-updates 10; 
load balance max seconds 5; 

mclt is only set on the primary and determines the length of leases when in failover on the non-primary ... from the man page: 

The mclt statement 

mclt seconds; 

The mclt statement defines the Maximum Client Lead Time. It must be specified on the primary, and may not be specified on the secondary. This is the length of time for which a lease may be renewed by either failover peer without contacting the 
other. The longer you set this, the longer it will take for the running server to recover IP addresses after moving into PARTNER-DOWN state. The shorter you set it, the more load your servers will experience when they are not communicating. A 
value of something like 3600 is probably reasonable, but again bear in mind that we have no real operational experience with this. 
> From: "Randall C Grimshaw" <rgrimsha at>
> To: dhcp-users at
> Sent: Tuesday, August 7, 2012 2:21:48 PM
> Subject: critical FYI secondary in partner-down

> Internet Systems Consortium DHCP Server 4.1.1-P1 as distributed by
> Red Hat Enterprise Linux Server release 6.3 (Santiago) and possibly
> other versions.

> To my great surprise when I brought up my secondary in partner-down
> mode, all of the leases issued had a zero duration. This was quite
> disruptive - All of my windows machines with dynamic leases failed.

> The work-around is to change the server to primary. (but it took a
> bit of work and dented reputation to determine this)


> has anyone else seen this?

> Randall Grimshaw rgrimsha at
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at
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