"deny duplicates;" not working?
stenc at s-carlsen.dk
Tue Jan 8 19:06:20 UTC 2013
On 08/01/13 19:51, Neff, Glen wrote:
> We have proprietary network devices that use rely on DHCP for
> configuration. We're using a standard 72 hour lease time, and we rely
> on the IPs to not change, so long as these devices aren't offline for
> much more than a reboot.
> Static assignments by MAC address are not feesible for our purposes.
> The problem that we are encountering is that periodically these
> devices must have their firmware updated and these updates are causing
> the UID sent in the DHCP request to be changed.
The main piece of information to identify a client is actually the UID,
so with a new UID -> a new client, obviously it can not get the same IP,
that is reserved for the old client.
You may have luck looking into classes and subclasses. Possibly with
"spawn". I have never used these features but I have a feeling they may
actually do what you need.
Use the hardware = MAC to create your subclass and that could be
independant from the UID - I think.
> Here's an example of three entries taken from the dhcpd.leases file on
> the server: http://pastebin.ca/2299463
> The first entry was was generated by a reboot early in the day.
> The second entry was "control case" reboot made before we updated the
> firmware on the client device. Notice how it's identical to the
> first, with the exception of the times.
> The third entry is after the firmware update. Notice that the MAC
> address remains the same, however the UID has changed, so the server
> issued it a new IP.
> In consulting dhcpd.conf(5) I found "deny duplicates;" which sounded
> like a magic bullet workaround, so I added it to the subnet
> declaration in dhcpd.conf file, but the problem remains the same (in
> tests with other of the same type devices and firmware upgrade scenario).
> The server version is 4.2.4, running on FreeBSD v8.2-RELEASE. It's
> built via the ports system: isc-dhcp42-server-4.2.4_1
> There is a DHCP-relay involved - it's configured on the VLAN interface
> of a Cisco Nexus 7010, running NX-OS v 5.2(3a).
> Any insite would be appreciated.
> * Glen R. J. Neff
> * USD Lab Operations Infrastructure Team
> * glen.neff at emc.com
> * EMC^2 == E^2
> dhcp-users mailing list
> dhcp-users at lists.isc.org
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"MALE BOVINE MANURE!!!"
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