host-identifier and option 82

[David Ganor]

Hi Michal,
Thank you for the info, but my problem is to get the option#82 in the
DHCPDiscover and in the DHCPRequest messages, so I don't have the option to
set the giaddr.


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 Michal Van?o
Sent: Thursday, February 02, 2012 9:42 PM
To: Users of ISC DHCP
Subject: Re: host-identifier and option 82

Hi,

I probably found a solution for this. This works for Cisco CMTS. If you need
to force all unicast RENEW request to go through relay agent (to force CMTS
to insert option 82), just set server-id to giaddr. This way, all unicast
request will go to relay agent and it will deal with them the same way as
with broadcasted requests. Just testing this on my CMTS.

regards
michal

On 27.1.2012, at 13:30, Simon Hobson wrote:

> Michal Vanão wrote:
> 
>> The only problem I've seen so far is that the client fails to renew its
IP after T1 passes (because RENEWING DHCPREQUEST is sent directly to server
bypassing agent relay). If I understand the RFC correctly, client should
"succeed" in REBIND (after T2 passes) because REBINDING DHCPREQUEST is
broadcasted hence seen by relay agent. Relay agent shall add opt 82 into
DHCPREQUEST in this stage. With properly inserted opt 82, server should be
able to match static host decl again.
>> 
>> Is this the way it is supposed to work?
> 
> I suspect it's one of those "grey areas" ! If a relay agent only adds
Option 82 to packets it picks up through "normal" operation, then what
you've observed is correct.
> 
> While it's not something I've used myself, from comments on this list I
get the impression that some equipment will snoop traffic and still add
Option 82 to non-broadcast DHCP packets. That does of course require that
the relay agent is in the same path as the normal unicast packets - ie a
unicast DHCP packet will pass through the same interface, and thus get the
same Option 82 value as it would if broadcast.
> 
> --
> Simon Hobson
> 
> Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed 
> author Gladys Hobson. Novels - poetry - short stories - ideal as 
> Christmas stocking fillers. Some available as e-books.
> _______________________________________________
> 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