DHCP Relay Option

jayadhanesh · 05-11-2009, 11:00 PM

Hi,
I have a DHCP relay to forward the DHCP messages between the
dhcp client and server. I have to add the Agent Information option,
(82) to the DHCP discover packet from the Relay to the server.
This generally includes the Circuit Id and Remote Id. I also need
to add the Relay IP address so that the server sends a unicast
DHCP offer with the destination ip as Relay IP.
What is the sub option code for agent ip address in Agent information
option?

Thanks,
Dhanesh.

kpraveen455 · 05-13-2009, 08:39 AM

What do u mean "agent Ip address" in Agent Information option?
The agent IP will go in 'giaddr' field of DHCP packet. And it will be the IP address of the interface on which the packet was received.

jayadhanesh · 05-14-2009, 01:45 AM

Hi,

When the DHCP server is responding with a DHCP offer, the destination
address of the OFFER is the address that is being offered to the client.
The agent is not able to receive this packet as the destination address
is not that of the agent.

So, if I fill the gateway address as the address of the agent IP address,
then the destination address in OFFER should be that of the agent.

Thanks,
Dhanesh.

kigchan · 02-12-2010, 09:08 AM

The agent is not broadcasts the offer to the listen interface

Quote:

Originally Posted by jayadhanesh

Hi,

When the DHCP server is responding with a DHCP offer, the destination
address of the OFFER is the address that is being offered to the client.
The agent is not able to receive this packet as the destination address
is not that of the agent.

So, if I fill the gateway address as the address of the agent IP address,
then the destination address in OFFER should be that of the agent.

Thanks,
Dhanesh.