once lease per client is not working

Douglas Armstrong doug at ovationdata.com
Mon Dec 18 01:14:12 UTC 2006

VKR V wrote:
> Interesting. If client gets the same IP again and again by enabling one-lease-per-client (besides enabling deny duplicates) then there is another problem described below -
>   Once client gets IP address and then if it is rebooted it sends DHCPDISCOVER message (without requesting for previously allocated IP) to DHCP server. The server in-spite of have the info about client ID and MAC in lease file and lease time is not expired, it allocates new IP.
>   Am I missing something?
>   VK
The client should always get the same IP if it is attaching to the same 
network. If it has moved, and the previous address is invalid for the 
sub net to which it is attached, it will be issued a (new) valid 
address. If one-lease-per-client is set the server will terminate and 
leases that the client holds on other subnets. per the man page:

one-lease-per-client flag;

If this flag is enabled, whenever a client sends a DHCPREQUEST for a 
particular lease, the server will automatically free any
other leases the client holds. This presumes that when the client sends 
a DHCPREQUEST, it has forgotten any lease not men-
tioned in the DHCPREQUEST - i.e., the client has only a single network 
interface and it does not remember leases it’s holding
on networks to which it is not currently attached. Neither of these 
assumptions are guaranteed or provable, so we urge cau-
tion in the use of this statement.

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