Reservation best practices?

[Joshua Beard]

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;

		# 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;
}