Re: problems with having two DHCP servers...
On Thu, 2012-01-05 at 15:55 -0500, Rick Thomas wrote:
> On Jan 5, 2012, at 1:40 PM, John A. Sullivan III wrote:
>
> > On Thu, 2012-01-05 at 12:57 -0500, Rick Thomas wrote:
> >> A limited amount of redundancy is good. If one goes down, the
> >> network
> >> can still limp along.
> >>
> >> Anyway, that's the theory.
> >>
> >> Rick
> >>
> >> On Jan 5, 2012, at 10:07 AM, Osamu Aoki wrote:
> >>
> >>>> I'm not the OP, but I do have this problem. When I try to do an
> >>>> install (wheezy) on a network with two DHCP servers, the
> >>>> installer's
> >>>> dhcp-client never seems to get an IP address -- even though the two
> >>>> servers are both responding and both giving the same IP address.
> >>>
> >>> Then why have 2?
> >>
> >>
> > The problem is when they are administering addresses in the same
> > range.
> > I've not configured DHCP for a long time so maybe this is common now
> > and
> > the problems have all been resolved but, in the past, if one wanted
> > redundancy, one would administer different ranges on the same subnet
> > so
> > that there would be no conflicts. Hope that helps - John
>
> Yes, that does seem to fit.
>
> The two servers have different ranges for their "dynamic" clients
> (i.e. transient laptops with no fixed IP address) but for the "static"
> clients (desktops with a fixed IP address) there is only one address,
> so both servers have to provide the same address.
>
> So... when I do an install for a machine with an unknown Ethernet Mac
> address -- hence getting it's IP from one or another of the "dynamic"
> ranges -- all goes well. It's only when I attempt to install a
> machine with a known Mac address (hence a single static IP) that I run
> into trouble.
>
> Somehow, I would have thought it should be the other way round --
> conflicting responses would cause problems, not two responses that
> both say the same thing. Sigh! Just shows how much I know...
>
> So is there a way to have both redundancy *and* reliable installs?
>
> Thanks for any help,
>
> Rick
>
> PS: As others have noted, it seems to affect only the installer's DHCP
> client. After the reboot, there's no problem -- with either static or
> dynamic IP...
>
Hmm . . . could you install with a manual IP address and then simply
change the configuration once the installation is done? - John
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