Option 82 renew/rebind problem

[Glenn Satchell]

>Date: Thu, 10 Jul 2008 08:07:04 +0200
>From: Andre Schubert <andre at km3.de>
>To: dhcp-users at isc.org
>Subject: Re: Option 82 renew/rebind problem
>
>On Wed, 09 Jul 2008 23:21:58 +0200
>Claus Holm Christensen <iscdhcp at claushc.dk> wrote:
>
>> Andre Schubert wrote:
>> > But i have seen some CPEs that send their packets directly to the 
dhcp-server asking to renew the lease.
>> > When this happens, the relay agent has no chance to add the agent 
information to the packets.

This is normal bahaviour. DHCPDISCOVER is broadcast, but DHCPRENEW is
unicast direct to the dhcp server. Have a look in dhcpd.leases for a
lease on one of these devices - it should have recorded the dhcp relay
options in the lease information so they can be re-applied for unicast
packets.

>> > I searched through the archives and found the following snipped:
>> 
>> Maybe you are looking for the stash-agent-options parameter?
>> 
>>  From dhcpd.conf manual (ver 3.0.6):
>> 
>> > If the stash-agent-options parameter is true for a given client, the server 
will record the relay agent information options sent during the
>> > client’s initial DHCPREQUEST message when the client was in the SELECTING 
state and behave as if those options are included in all subsequent
>> > DHCPREQUEST messages sent in the RENEWING state.  This works around a 
problem with relay agent information options, which is that they usually
>> > not appear in DHCPREQUEST messages sent by the client in the RENEWING 
state, because such messages are unicast directly to the server and not
>> > sent through a relay agent.
>> 
>> Hope this helps.
>> 
>
>thanks for your answer, but stash-agent-options is already set to true and 
doesnt help in this place.
>It seems that stash-agent-options comes in after a lease has been assigned and 
the agent information options
>are put onto the outgoing packet.
>
>Maybe is it possible to get the dhcp-server working with such a scenario ?

Like I said above, this is normal behaviour and dhcpd handles it. Check
the leases file to see what infoprmation is stored in the lease. Then
the next step is to see either why the option-82 information is
missing, or why it is not being used for subsequent renewals.

Is unicast traffic from the CPE to the dhcp server permitted? ie
there's no firewall blocking packets or missing routes?

regards,
-glenn