dhcpd.leases question

[Nicolás Valera]

On 06/06/2012 11:26 PM, Glenn Satchell wrote:
>> On 06/06/2012 11:20 AM, Glenn Satchell wrote:
>>>> On 06/05/2012 10:28 AM, Glenn Satchell wrote:
>>>>> On 06/05/12 23:10, Glenn Satchell wrote:
>>>>>> On 06/05/12 22:26, Nicolás Valera wrote:
>>>>>>> Hi, sorry about my ignorance but, what does it means "rewind binding
>>>>>>> state free;" in dhcpd.leses file?
>>>>>>> Thanks in advance!
>>>>>>> Nix.
>>>>>> Hi Nicolás
>>>>>>
>>>>>> The dhcpd.leases man age describes the format of the leases file.
>>>>>>
>>>>>> binding state state; next binding state state;
>>>>>>
>>>>>> The binding state statement declares the lease's binding
>>>>>> state. When the DHCP server is not configured to use the
>>>>>> failover protocol, a lease's binding state will be either
>>>>>> active or free. The failover protocol adds some additional
>>>>>> transitional states, as well as the backup state, which
>>>>>> indicates that the lease is available for allocation by the
>>>>>> failover secondary.
>>>>>>
>>>>>> A binding state of "active" means there is a client using this
>>>>>> particular lease now.
>>>>>>
>>>>>> A state of "free" means there is no client using this lease at the
>>>>>> moment and it is available to be given out by the server.
>>>>>>
>>>>> Sorry about that - it would be helpful if I read the question a bit
>>>>> more closely!
>>>>>
>>>>> Rewind binding state is used in failover. If the two servers go into
>>>>> communications-interrupted mode where they lose contact with each
>>>>> other, normally a particular server can only hand out new leases from
>>>>> it's share of the free pool. The idea is to allow it to reset the
>>>>> binding state of a lease so that it can re-issue the IP address. This
>>>>> is a fairly complex optimisation of the failover conditions which
>>>>> would not occur in normal operation and only rarely if failover
>>>>> situations, so it is something you shouldn't worry about too much.
>>>>>
>>>> Thanks for the answer!
>>>> but i'm not using the failover option, why my leases file contains
>>>> that?
>>>>
>>>> Thanks again and sorry about my English!
>>> This is a comment from the source code in server/failover.c
>>>
>>>            * In failover rules, a server is permitted to work forward in
>>> certain
>>>            * directions from a given lease's state; active leases may be
>>>            * extended, so forth.  There is an 'optimization' in the
>>> failover
>>>            * draft that permits a server to 'rewind' any work they have
>>> not
>>>            * informed the peer.  Since we can't know if the peer received
>>> our
>>>            * update but was unable to acknowledge it, we make this change
>>> on
>>>            * transmit rather than upon receiving the acknowledgement.
>>>
>>> rewind_lease_state is mentioned in a few other source files. It seems to
>>> be default behaviour to include it in the leases file, even when
>>> failover
>>> is not configured.
>>>
>>> regards,
>>> -glenn
>> Tanks a lot!
>> the last one:
>> can i remove from the leases file without any consequences and then move
>> it to the new dhcp server?
> Probably, but the new dhcp server will just write out the rewind line
> again, so easier to just leave the file as is.
>
> regards,
> -glenn
Glenn, thanks for your help!
Best regards,
Nix.