DHCP Static binding not working as expected??

[chamara samarakoon]

Hi,
As you explain first part is correct.  Regarding the sub net declaration,
what I posted is wrong,very sorry about that
in my real setup I have used sub net declaration which is having only 1ip.
Thanks,
Chamara
 On Sep 10, 2012 12:37 PM, "Simon Hobson" <dhcp1 at thehobsons.co.uk> wrote:

> chamara samarakoon wrote:
>
>  subnet 51.101.0.0 netmask 255.255.224.0 {
>> option ntp-servers 172.17.0.1;
>> deny client-updates;
>> authoritative;
>> option broadcast-address 51.101.31.255;
>> option routers 51.101.0.1;
>> max-lease-time 31536000;
>> default-lease-time 31536000;
>> pool {
>> failover peer "XXXX";
>> deny dynamic bootp clients;
>> range 51.101.0.10 51.101.0.254;
>> }
>>
>
>
>
>
>  /etc/dhcp_static_lease/dhcp_**static_conf/dhcpd_static.conf-**
>> ------------------------------**---
>>
>> include "/etc/dhcp_static_lease/51.**101.0.0.txt";
>>
>>
>> ------------------------------**------------------------------**
>> ------------------------------**------------------------------**---
>>
>> /etc/dhcp_static_lease/51.101.**0.0.txt-----------------------**
>> ------------------------------**----------------
>>
>> host 51.101.0.10{
>>                        hardware ethernet 00:20:d2:3a:51:69;
>>                     fixed-address 51.101.0.10;
>>                     }
>>
>
>
> Well there is one problem. Defining a static address does **NOT** exclude
> it from being offered as a dynamic address if it is still in a pool/range.
>
>
>
>  2.Unplug device A and change the static conf MAC to B's MAC(Restart dhcpd
>> server) and Plug device B
>>
>
> What does this mean ?
> I read this as you edited /etc/dhcp_static_lease/51.101.**0.0.txt and
> changed the MAC address for the host statement to that of device B and
> restarted the server - is that correct ?
>
> If so then you you observe is "correct" behaviour - correct in as much as
> what you told the server to do.
>
> You plug in device A. It gets a dynamic lease which is recorded in the
> lease file.
> You unplug device A, manually edit the MAC address in the config file to
> that of B and restart server. At this point, there is a lease in the leases
> file for device A, and a static assignment for device B
> You plug in device B. It gets offered the static assignment - which does
> not create a lease record.
> You plug in device A. It has an already active lease for the same address
> so this is selected. The ping-before-offer check detects device B and the
> lease is abandoned. Because you only have one address in the range, the
> server then attempts to reclaim abandoned leases in order to free up an
> address.
>
> However, while you say there is only one address in the range, your config
> you posted shows a whole subnet - 245 addresses in the range.
>
>
>
> For what you appear to be trying to do, you may be better off with
> reserved leases.
>
> --
> Simon Hobson
>
> Visit http://www.**magpiesnestpublishing.co.uk/<http://www.magpiesnestpublishing.co.uk/>for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
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