Upgrade from 3.0.2 to 3.0.4 and some strange changes

Simon Hobson dhcp1 at thehobsons.co.uk
Tue Oct 17 08:11:06 UTC 2006

Tom Schmitt wrote:

>  > It has been confusing since the dawn of time ("no free leases" does
>  > not mean no leases are free).  I'd love to make it not confusing.

>Okay, maybe I'm stupid. But if "no free leases" does not mean no 
>leases are free, what the h... does it mean?


It means "no free leases", but that does not mean there are no leases 
free. It means that there are no leases available which the server is 
allowed to give to this client if you see the subtle difference - 
consider this config snippet :

pool {
   range ;
   allow members of "group1" ;
pool {
   range ;
   deny members of "group1" ;

Here we have a fairly common situation where clients are grouped by 
some criteria so that some clients go in one pool, and other clients 
go in another pool. Suppose that there are no clients matching the 
criteria for class "group1", this means that all clients will get 
leases from the second pool.

If you have 11 active clients, then you can see there will be a 
shortage of IPs and so the 11th client will not get an address (no 
free leases) even though the first pool is still empty.

Whilst I'm not that familiar with failover, I believe there are also 
situations where one server may not be able to allocate an address 
because any addresses which are currently free are not available for 
THIS server to give out because it is 'owned' by the peer. So once 
again, whilst there are free addresses in the subnet/pool, THIS 
server isn't able to hand any of them out and so there are again "no 
free leases".

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