Good old "peer holds all free leases" appearing in a (formerly) very stable setup

Sten Carlsen stenc at
Tue Feb 18 17:32:21 UTC 2014

On 18/02/14 13:37, Nicolas Ecarnot wrote:
> Hi,
> We have setup a complex DHCP infrastructure 5 years ago, and it is very
> very stable and working very nicely :
> - 10 rhel5 servers, serving around 150 shared-networks for 150 physical
> sites
> - in every network resides mostly one pool, sometimes 2, and rarely more
> - every pool is "failovered" by a couple of two physical servers
> - we are using DhcId classes successfully
> - our router are using dhcp-helper setup to correctly relay the dhcp
> traffic
> Tests were made, time has passed, all this setup is SVN-versionned, we
> frequently change things/values/subnets, but we never change the basics
> described above, we use it every day and we think we have a clear view
> of it. It is all working FINE.
> Today, in a subnet, I just wanted to add a pool which access is
> restricted to a new class. As usual, I wanted this pool to be manageable
> by a server and its failover peer.
> What I get is the good old "peer holds all free leases" error, that I
> learned NOT to trust since years, as it appeared even when not related
> at all to leases issues.
> The subnet looks like :
> shared-network dhcp51-dsi {
>   subnet netmask {
>     option subnet-mask;
>     option routers;
>     option domain-name-servers,;
>   }
>   pool {
>     allow members of "oldStableClass";
>     failover peer "serv-net-adm1_serv-net-adms1";
>     deny dynamic bootp clients;
>     range;
>   }
>   pool {
>     allow members of "brandNewClass";
>     failover peer "serv-net-adm1_serv-net-adms1";
>     deny dynamic bootp clients;
>     range;
>   }
> }
> You can see there are 2 servers implied :
> - serv-net-adm1
> - serv-net-adms1
> Our dhcp test client is a windows XP which NIC got setup with a dhcid
> class like its thousand office neighbors around.
> Here are strange things I witnessed :
> - When restarting the daemon on adms1, the log file is showing the
> shared-networks it will manage, but sometimes I see "dhcp51-dsi" missing...
> - I tried to completely remove the failover setup, and to entrust
> net-adm1 only to manage this subnet. The error message is changing into
> "No free leases". This makes no sense to me as I think/know the pool is
> far from full. I'm using the dhcpd-pools to confirm it and it agrees
> with me.
Sounds a bit like a CLASS issue. This is what I would expect if for some
reason the host did not match either class.
I might test with a third pool that is denied for both classes, just to
see if that would catch it.
> I had a (read-only) look at the lease file, and it does not show any
> reference to this subnet, though it appears in the log file when
> restarting this server (net-adm1).
> I must admit I'd be glad to get some advices on things to check, even
> the obvious ones I may have skipped.
> You'll find below the versions used and you'll note these are not recent
> ones, but I think that is not relevant because this whole setup is
> running fine as is since years and no additional weird features is
> required there.
> - Redhat RHEL 5.3 64 bits
> - isc dhcp 3.0.5-18.el5
> Regards,

Best regards

Sten Carlsen

No improvements come from shouting:


More information about the dhcp-users mailing list