Failover issues

Shlomo Dubrowin shlomo at
Wed May 31 13:46:01 UTC 2006

I understand that the secondary won't go into "partner down" state, but
shouldn't the secondary give out it's "backup" leases?  When the primary is
down, no leases are being given out.  From what I've read, the secondary
should still be handing out it's automatically created "backup" scope of
IPs.  Is this not correct? or does the "Communications interrupted" mode
cause problems with that?

On 5/31/06, Simon Hobson <dhcp at> wrote:
> Shlomo Dubrowin wrote:
> >OK,  So I have failover configured and the primary is giving out leases
> as
> >it should.  Now, I want to test the failover.  What I have been doing is
> >shutting down the service on the primary and expecting the secondary to
> >automatically take over.  However, in the leases file on the secondary,
> I'm
> >seeing that it believes it's own connectivity is down and not that of the
> >primary.  So, when the primary fails, the secondary thinks it has a
> problem
> >with itself and doesn't give out leases.  Any ideas why this isn't
> working
> >as expected?
> Does it by any chance go into "Communications interrupted" mode ?
> I'm sure one of the failover experts will correct me if I'm wrong,
> but the servers will not go into partner down mode automatically -
> this is something you have to do manually. The reason given is that
> there are failure modes (in particular, routing errors or failure of
> an out-of-band inter server link) which can cause communications
> interrupted but leave both servers able to communicate with clients -
> having both server go into partner down and offering leases across
> the whole range would result in "a certain amount of confusion".
> Dig back through the archives, there's been a number of suggestions
> for methods to monitor the peer and put the local server into partner
> down via omapi (IIRC).
> Simon

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