Option 82 fast change

[Marc Perea]

Hi Colin,
It sounds like I'm doing the exact same thing as you.

I too would like to see an answer or recommendation to this. I tried using omshell/omapi, but couldn't expire a lease early.

What we've done is script a process that terminates dhcpd, goes in and looks for the lease (we know the IP which is on the first line of the lease because of a separate database that tracks the customer to option 82 circuit to "static" IP), deletes all lines from the IP to the closing curly bracket, and then restarts dhcpd. This script is called from a webpage with parameters supplied by our support team.

This method is working for us at the moment, but I'm not sure it's the best method, or if it will scale well. As far as I know, this is the only method that'll get the job done.



Date: Wed, 10 Sep 2008 18:57:23 +0100 (BST)
From: Colin Cooper <C.Cooper at compserv.gla.ac.uk>
Subject: Option 82 fast change


Hello

We have a requirement to always provision the same IP address to a particular
location, this we achieve by using option 82 along with some class and pool definitions
which define a class for the port and a pool of one address for the class.
This appears to work fine.

The problem is that the computer at the location changes quite frequently
and seldom if ever releases its lease prior to being removed. The next machine
to be attached cannot get the single available IP number as the lease is out for
the previous machines address.

Is there a method of always answering the initial dhcprequest ignoring the fact that the IP
address appears to already be leased ( not something a dhcp server would normally do )
or in someway not mapping to the hardware address at all.
if the switch port going down release the lease that would solve the problem nicely.

The setup is a cisco 2960 10/100 switch and a pair of linux 1u with isc dhcpd 3.0.5

Very short leases are not really on in case of server failure and the impact that would
potentially have on the use of the computer.

Thanks in advance for any help





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The University of Glasgow, charity number SC004401

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End of dhcp-users Digest V3 #225
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Marc Perea
Network Support Engineer
SRT Communications, Inc.