No Free Addresses?

Sten Carlsen stenc at
Mon Dec 13 23:06:16 UTC 2010

The way I understand it, each server has a part of the total address
space and balances this with its partner at intervals.

When the communication between them breaks they do not automatically
assume the other server is down, it is your responsibility to tell the
remaining server that the other is really dead, not just unable to

Until the server gets the information that its partner really is dead,
it will not hand out leases belonging to the partner -> effectively you
are missing half your address space until then.

I never used failover, many on this list are using them, I assume they
will be able to help you out here.

On 13/12/10 23:49, Bob Proulx wrote:
> Sten Carlsen wrote:
>> Has the remaining server been set into "partner down" state?
> No.  But that would not have addressed the primary problem of not
> having enough IP addresses available.  Each machine in the failover
> pair needs to be able to independently support the entire network.  If
> that only happens by manually putting one machine into partner-down
> then that isn't a truly redundant system.
> Putting the single server into partner-down would have increased the
> pool size the same as I did manually.  But then I am still left with
> the same questions about how big of a pool do I need and how can I
> tell?
> But that also opens a second less important issue that I hadn't
> debugged yet.  When I tried to use omshell to do that it failed to
> connect.
>   # omshell
>   > connect
>   dhcpctl_connect: no more
>   > server
>   > connect
>   dhcpctl_connect: no more
>   > port 647
>   > connect
>   dhcpctl_connect: no more
> I wasn't able to talk to the running daemon to actually switch it to
> partner-down.
> When I strace'd the operation I get the following result.
>   connect(4, {sa_family=AF_INET, sin_port=htons(647), sin_addr=inet_addr("")}, 16) = -1 EINPROGRESS (Operation now in progress)
> I consider this a separate issue but since you asked any hints there?
> Bob
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> dhcp-users mailing list
> dhcp-users at

Best regards

Sten Carlsen

No improvements come from shouting:


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