No Free Addresses?

Simon Hobson dhcp1 at
Tue Dec 14 19:11:28 UTC 2010

Bob Proulx wrote:

>Putting a server into partner-down requires manual interaction.  That
>negates a primary benefit of having redundant servers.  If failover
>required manual interaction then it would be a less useful concept.
>Fortunately I am pretty sure that isn't the case and failover actually
>does work just fine regardless of what this thread would have someone
>It was asked if I *had* put the server into partner-down.  I am sure
>it was asked with the simple idea that it would increase the IP space
>by reclaiming that given to the other half of the split and workaround
>the no free lease problem.  I don't think it was suggested as a
>solution to not having enough free IP addresses but just as workaround
>to keep things moving.

You seem to have missed something. It was suggested as simple step 
that is pretty well guaranteed to fix the problem. If your failover 
pair had enough addresses working together, then one of them in 
partner down mode should also have sufficient.

>That was a fine question.  But please don't
>get the idea that it is a desirable state.  Needing partner-down is an
>indication that you don't actually have redundancy.  It really is only
>good as a workaround to not having enough IPs in the address pool.

Rubbish, it's simply that the failover isn't 100% automatic BY 
DESIGN. If you make it automatic (which you can do) then it's truly 
redundant in the terms you seem to be meaning - as in "lights out, no 
admin intervention required"

>  > Doesn't matter - just put the remaining one into partner down state.
>Sorry but no.  If you *need* to put a server into partner-down then
>you do *not* have a redundant dhcpd server.  If you are operating in
>that mode then you might as well not be using failover at all.
>>  When the other recovers (or is replaced) they will sort themselves
>>  out automatically.
>Yes of course.  But that is unrelated.

Sorry, I **really** don't understand where you are coming from here. 
You have two servers, if one fails the other can pick up it's load 
(and this CAN be automatic if you wish). When the failed server is 
fixed, they automatically resume normal shared operations.

I really, really cannot see how you call this "not redundant" !

Sorry if this sounds a tad aggressive, but you seem to be approaching 
this with a certain mindset that failover is "not redundant" and is 

Simon Hobson

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