ISC Dhcp Failover behavior for INIT-REBOOT scenario
Glenn Satchell
glenn.satchell at uniq.com.au
Mon May 24 11:39:12 UTC 2010
Hi Ravi
I don't have an answer for you. I suggest that some testing and reading
the source code may be the answer. A good place to start might be the
file server/failover.c in the source distribution.
regards,
-glenn
On 05/24/10 18:52, ravi kumar wrote:
> <Resending the mail, as there is no response>
> Can someone please throw light on ISC's implementation.
>
> regards
> Ravi
> On Thu, May 20, 2010 at 8:39 PM, ravi kumar <ravikumar.lrk at gmail.com
> <mailto:ravikumar.lrk at gmail.com>> wrote:
>
> I would like to know the behavior of Dhcp Failover implementation in
> INIT-REBOOT scenario. Is the following highlighted part taken care
> of in Failover implementation ?
> Also, would like to know if anyone has come across any Client, that
> behaves in below specified manner : Request is sent during
> INIT-REBOOT, though Client doesnot have valid lease.
> <Copy-Paste from Dhcp Failover draft
> [*draft-ietf-dhc-failover-12.txt*
> <http://tools.ietf.org/html/draft-ietf-dhc-failover-12.txt>]>
> One troublesome issue is that of the DHCP client responsibility when
> sending in DHCPREQUEST/INIT-REBOOT requests. While the original
> DHCP
> RFC was written to require a DHCP client to have time left to run on
> the lease for an IP address if the client is sending an INIT-REBOOT
> request, it was sufficiently unclear that some client vendors didn't
> realize this until recently. Since the INIT-REBOOT request was sent
> with the IP address in the dhcp-requested-address option and not in
> the ciaddr (for perfectly good reasons), the similarity to the RENEW
> and REBINDING case was lost on many people.
>
> At present, the failover protocol does not assume that a client send-
> ing in an INIT-REBOOT request necessarily has a valid lease on
> the IP
> address appearing in the dhcp-requested-address option in the INIT-
> REBOOT request.
>
> The implications of this are as follows: Assume that there is a DHCP
> client that gets a lease from one server while that server is unable
> to communicate with its failover partner. Then, assume that after
> that client reboots it is able only to communicate with the other
> failover server. If the failover servers have not been able to com-
> municate with each other during this process, then the DHCP client
> will get a new IP address instead of being able to continue to use
> its existing IP address. This will affect no applications on the
> DHCP
> client, since it is rebooting. However, it will use up an
> additional
> IP address in this marginal case.
> regards
> Ravi
>
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