How to configure dhclient to send option#82

David Ganor david at oliver-solutions.com
Mon Feb 6 12:14:57 UTC 2012


Hi Tom,
1. ONU doesn't run an IP stack (same as the OLT). Also, since it's an EPON
ONU, it's unaware of the DOCSIS/DPoE management going on at the OLT and host
side.
2. In any case, the relay info is on behalf of machines connected to the
ONU, not the ONU itself.
3. Can I run both the dhcrelay and dhclient on the same machine and cascade
them? Wouldn't DHCPDiscover/Requests generated by the client and then
trapped by the relay be sent with the option#82 in them?


Regards,
David Ganor


-----Original Message-----
From: Tom Martinson [mailto:thomas.s.martinson at gmail.com] 
Sent: Monday, February 06, 2012 12:38 PM
To: david at oliver-solutions.com; Users of ISC DHCP
Subject: Re: How to configure dhclient to send option#82

option 82 is defined on the relay agent.   In the DOCSIS world option 82
added to the discover by the CMTS.  If the OLT does not relay with option 82
then I guess you have two choices.  1 see if the ONT will somehow send the
option 82 configuration you are looking for. Or you might be able to match
based on the Vendor OUI in the MAC. 

You may want to log into CableLabs doc zone and check what the specs say for
DPoE.  



Tom Martinson


On Feb 6, 2012, at 4:39, "David Ganor" <david at oliver-solutions.com> wrote:

> No we do not build nor design the OLT. In some case it doesn't even 
> run an IP stack...
> 
> 
> Regards,
> David Ganor
> 
> 
> -----Original Message-----
> From: dhcp-users-bounces+david=oliver-solutions.com at lists.isc.org
> [mailto:dhcp-users-bounces+david=oliver-solutions.com at lists.isc.org] 
> On Behalf Of Rudy Zijlstra
> Sent: Monday, February 06, 2012 10:39 AM
> To: dhcp-users at lists.isc.org
> Subject: Re: How to configure dhclient to send option#82
> 
> On 02/06/2012 09:33 AM, David Ganor wrote:
>> OLT, in this case, can only pass the DHCP packets to the host (the
>> DPoE-system) and cannot modify it.
>> I need a solution that is controlled by the host...
>> 
> Yet the OLT is normally the one to run the dhcp-forwarder, which is 
> the entity responsible to include option 82
> 
> Are you building/designing the OLT?
> 
> Rudy
> 
>> Regards,
>> David Ganor
>> 
>> 
>> -----Original Message-----
>> From: Jeff Waller [mailto:jeffw at cnxntech.com]
>> Sent: Sunday, February 05, 2012 8:19 PM
>> To: david at oliver-solutions.com; Users of ISC DHCP
>> Subject: Re: How to configure dhclient to send option#82
>> 
>> Usually the OLT can be configured to modify the contents of the DHCP 
>> packets to include option 82.  Check with vendor.
>> 
>> On Feb 5, 2012, at 7:11 AM, David Ganor wrote:
>> 
>>> Hi Niall,
>>> Well, without going into too many details...
>>> 1. The system is a control host for a DPoE (DOCSIS Provisioning over
>>> EPON)
>>> network:
>>>    a. the DPoE-system is a Linux machine connected to an EPON 
>>> manager box, called an OLT.
>>>    b. The OLT manages/controls an EPON optical network, in which 
>>> each node is terminated by a remote "MODEM", called an ONU.
>>>    c. The ONU services network devices, such as computers, VOIP 
>>> phones,
> 
>>> set-top boxes etc. These devices run an IP stack and needs to get an 
>>> IP address from a DHCP server.
>>>    d. An ONU doesn't run an IP stack, but is managed via SNMP, 
>>> through an agent running on the system.
>>> 2. The system runs DHCP clients to get IP addresses for managed 
>>> entities
>>> (ONUs) and also acts as a DHCP relay, on behalf of non-managed, 
>>> remote devices.
>>> 3. Whenever a managed entity is connected and the associated SNMP 
>>> agent requests an IP address, it should also add
>>> option#82-suboption#9 with enterprise number 4491 (indicating 
>>> CabelLabs Inc., the owner of the DPoE and DOCSIS specs) 4. The 
>>> dhcrelay, as a standalone process, can probably be used for the 
>>> phase of getting the IP address, but doing the actual relaying job 
>>> between
>>> 2 interfaces, on separated IP subnets is not feasible:
>>> the DHCP messages from, and to, the non-managed remote devices don't 
>>> go through a "regular" (Linux) Ethernet interface - it's a special 
>>> host-control interface with a special control application (which we
>>> develop...)
>>> 
>>> I hope this not-so-short-after-all background overview makes my 
>>> question a little clearer, so to summarize:
>>> Can I, somehow, run/connect/configure something(s) so that the 
>>> DHCPDiscover and DHCPRequest will include this option#82?
>>> 
>>> I know I can hard-code this option in the dhclient and re-build the 
>>> executable, but I would prefer not to...
>>> 
>>> 
>>> Thak you for yout time,
>>> David Ganor
>>> 
>>> 
>>> -----Original Message-----
>>> From: dhcp-users-bounces+david=oliver-solutions.com at lists.isc.org
>>> [mailto:dhcp-users-bounces+david=oliver-solutions.com at lists.isc.org]
>>> On Behalf Of Niall O'Reilly
>>> Sent: Thursday, February 02, 2012 11:58 AM
>>> To: Users of ISC DHCP
>>> Subject: Re: How to configure dhclient to send option#82
>>> 
>>> 
>>> On 2 Feb 2012, at 07:51, David Ganor wrote:
>>> 
>>>> I need to configure a dhclient to send option#82 with a specific
>>> sub-option #9 in the DHCPDiscover and in the DHCPRequest messages.
>>> 
>>>    I believe that that's a need which is architecturally beyond what 
>>> DHCP
>>>    is intended for.
>>> 
>>>    Option 82 is intended to be used for adding information to the DHCP
>>>    exchange which is available on the relay device (usually a router),
>>>    but not on the client.  By design, a client simply doesn't do 
>>> option
> 
>>> 82.
>>> 
>>>    From what you say, it appears to me that you need to communicate
>> some
>>>    property of the client to the server, and that this property is
>> known
>>>    (by configuration) at the client.  I think you should best choose an
>>>    appropriate option from among those that the client con be
>> configured
>>>    to send.
>>> 
>>>    Without further information about what you are actually trying to
>>>    achieve, and perhaps also about your network topology, it will be
>>>    difficult for anyone on the list to give you advice relevant to
>>>    your circumstances.
>>> 
>>> 
>>>    Best regards,
>>>    Niall O'Reilly
>>> 
>>> _______________________________________________
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>>> 
>>> _______________________________________________
>>> dhcp-users mailing list
>>> dhcp-users at lists.isc.org
>>> https://lists.isc.org/mailman/listinfo/dhcp-users
>> 
>> _______________________________________________
>> dhcp-users mailing list
>> dhcp-users at lists.isc.org
>> https://lists.isc.org/mailman/listinfo/dhcp-users
> 
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
> 
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users




More information about the dhcp-users mailing list