Reservation best practices?

[Barry Stear]

On Wed, Jul 13, 2011 at 9:51 AM, Joshua Beard <josh at hewbert.com> wrote:

>
> On Jul 12, 2011, at 2:53 PM, Joshua Beard wrote:
>
> >
> > On Jul 12, 2011, at 12:17 PM, Joshua Beard wrote:
> >
> >> Greetings,
> >>
> >> This is likely a rookie question, but I thought I'd ask the list.
> >>
> >> The scenario:
> >> We've received many new printers on our network this week, which already
> had hostnames preset to conform to our standards and were setup for DHCP.
>  My plan was to let them get DHCP and then reserve the address for them by
> using the MAC.
> >>
> >> After reading around, it looks like reservations don't work that way in
> ISC DHCP.  My understanding is that the reserved address cannot be in the
> lease pool.  Unfortunately, these printers have already received addresses
> in the pools of their respective subnets.
> >>
> >> Additionally, some of the folks setting them up may have already added
> these printers via their IP addresses to client machines.
> >>
> >> What's recommendations are there to handle this?  I'm thinking I'll have
> to set aside a block of addresses in each subnet that's not in the pool and
> reserve them in that and wait for them to make a new request, then adjust
> any client machines that are talking to them via IP.  Is this my best
> option?  Is there a clean way to do this with ddns in mind?
> >>
> >> Thanks in advance,
> >> Josh
> >
> >
> > Thanks for all the responses.  I ended up just setting aside a range from
> each subnet's non-pooled addresses and designating them for reservations and
> hacking together a couple of scripts to bulk import them into BIND and
> DHCP's configs.
> >
> >
>
> GAH!  I spoke too soon.  They're getting their reservations and talking -
> but only on their subnet.  They aren't getting the router/default gw from
> the DHCP server.  I have "option routers 172.30.xxx.xxx" for each subnet.  I
> tried doing the same on the reservation definition, but no dice.
>
> I hate to do this, and I hope it's not too much to ask, but I'd like to
> post part of my config to get any input.
>
> Thanks,
> Josh
>
>
>
> ddns-update-style interim;
> ignore client-updates;
> ddns-domainname "dsdk12.schoollocal.";
> ddns-rev-domainname "in-addr.arpa.";
>
> key dhcpupdate {
>        algorithm hmac-md5;
>        secret "---secret---";
> }
>
> zone dsdk12.schoollocal. {
>        primary 127.0.0.1;
>        key dhcpupdate;
> }
>
> zone 30.172.in-addr.arpa. {
>        primary 127.0.0.1;
>        key dhcpupdate;
> }
>
> option domain-name "dsdk12.schoollocal";
> option domain-name-servers 172.30.112.121
>


> option ip-forwarding off;
>
> default-lease-time 7200; # I'll adjust later
> max-lease-time 8000; # I'll adjust later
>
> option time-offset -17000;
> option ntp-servers 172.30.112.126;
>
> authoritative;
> log-facility local7;
>
> include "/etc/dhcp3/dhcpd.reservations.conf";
> include "/etc/dhcp3/printers.reservations.conf";
>
>
>
> Example subnet:
> subnet 172.30.112.0 netmask 255.255.240.0 {
>                authoritative;
>                option routers                  172.30.112.2;
>                 # This is the full range
>                #range 172.30.112.3 172.30.127.254;
>
>                pool {
>                range 172.30.115.1 172.30.127.254;
>                                option subnet-mask
>  255.255.240.0;
>                                option broadcast-address
>  172.30.112.255;
>                                option routers
>  172.30.112.2;
>                }
>
> } # // ITdept
>
>
>
> Example printer reservation:
> host vnbandk3920.dsdk12.schoollocal {
>    hardware ethernet 00:c0:ee:7d:bc:80;
>    fixed-address 172.30.176.243;
>
}

The reason why the printer is not picking that up is because it is specified
within the pool. Since the printer is not obtaining its IP from the pool you
need to specify anything you want to apply to the rest of the subnet outside
the pool such as above. At least I think so .. someone correct me if im
wrong.
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