How to sync a Linux secondary DHCP server?

[Thomas Markwalder]

Good morning:

That's correct, Glen.  When added via omapi, the reservation is tacked 
on to the lease-file, with the keyword "dynamic".  This tells the server 
to preserve the reservation across reboots.  The only way to convey it 
the peer server is to do so either through an omapi connection to that 
server,
or by adding it through some other means to the peer's configuration file.

Thank you, Glen, for your steadfast presence on the user's list. You 
routinely provide valuable insight to the many questions that arrive on 
the list. Your attentiveness to it is very much appreciated.  From all 
of us at ISC, thank you!

Cheers,

Thomas Markwalder
ISC Software Engineering

On 08/01/2018 09:07 AM, Glenn Satchell wrote:
> If, for example, you added fixed reservations using omapi, then you would
> need to register these same configuration with both dhcp servers.
>
> This is the only way to ensure there is consistent configuration on both
> servers.
>
> The leases files are different on the two servers, so you can't just copy
> the leases file from one server to the other.
>
> regards,
> -glenn
>
> On Wed, August 1, 2018 12:46 am, Sten Carlsen wrote:
>> Thanks, I did not know and I thought this should be part of the answer.
>>
>> On 31/07/2018 16.44, Thomas Markwalder wrote:
>>> Hello Sten:
>>>
>>> Those would also have to be manually sync'd. The fail over protocol
>>> does not extend to reservations.Â
>>>
>>> Regards,
>>>
>>> Thomas
>>>
>>> On 07/31/2018 10:21 AM, Sten Carlsen wrote:
>>>> Just to clarify, "host reservations" can be two things.
>>>>
>>>> Host statement, possibly with a fixed address statement -
>>>> synchronized via file transfer.
>>>>
>>>> Reservation in the leases file - how would these function in a fail
>>>> over pair?
>>>>
>>>>
>>>> On 31/07/2018 16.16, Thomas Markwalder wrote:
>>>>> Hello Sandra:
>>>>>
>>>>> Yes. Anything specified via configuration file must be sync'd
>>>>> outside of ISC DHCP.
>>>>> Fail over, in ISC DHCP, is based on draft RFC:
>>>>>
>>>>> https://tools.ietf.org/html/draft-ietf-dhc-failover-12
>>>>>
>>>>> It does not call for exchanging information beyond lease and server
>>>>> state information, and
>>>>> was written such that any two servers which adhere to it, should be
>>>>> inter operable.  At least
>>>>> that was the original intent.
>>>>>
>>>>> Host reservations are "a policy mechanism" and as such are not
>>>>> governed by RFCs. Thus they
>>>>> are entirely specific to DHCP server implementations.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Thomas Markwalder
>>>>> ISC Software Engineering
>>>>>
>>>>> On 07/31/2018 10:00 AM, Sandra Schlichting wrote:
>>>>>>> One point of clarification,  Host reservations are not synchronized
>>>>>>> between servers via fail over.  Any host reservations you have in
>>>>>>> one
>>>>>>> configuration file,  you must include in the peer server's
>>>>>>> configuration
>>>>>>> file.  For dynamic reservations (i.e. those that do not include a
>>>>>>> fixed
>>>>>>> address), the leases allocated for each host will be synchronized
>>>>>>> (assuming they come from within a FO pool), but not the actual
>>>>>>> reservation specifications.
>>>>>> So for the reservation I would have to rsync/scp them over?
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