Switch a client to fixed pool after dynamic ip delegation

Randall C Grimshaw rgrimsha at syr.edu
Thu Feb 28 18:14:35 UTC 2013

when you use dhcp to steer clients between pools, you are still using the allow or deny membership acl's - please recall that membership can be assigned by your classes. What is generally not documented is that your acl's should violate the generally held principal that allow/deny rules are exclusive in each pool. The documented principle holds true for initial leases but renewals seem to require an explicit deny in order to force the transition.
Randall Grimshaw rgrimsha at syr.edu


Sent: Thursday, February 28, 2013 11:34 AM
To: dhcp-users at lists.isc.org
Subject: Switch a client to fixed pool after dynamic ip delegation

Hello everyone,

I have an isc dhcp server.

The configuration is mixed between a dynamic pool
and some static fixed pools (with option agent circuit id).

That means:
a lot of clients get there ip from the pool dynamic.
a lot of clients get there ip "fixed" via the agent
circuit id option of the static fixed pool configuration.

My problem:
If I switch a client from the dynamic pool into the
fixed "area" the client send his next DHCPREQUEST
with the "old ip from the pool".

and...the dhcp server says "OK you could have that"
altough a fixed pool entry exists...

Is there any posiblity to tell the DHCP server if
a static fixed pool exists only use this?


Have anyone, any idea?

thanks a lot andy

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