Assigning IP Address Using Option 82 in one Subnet

Rico Zoss rico.zoss at
Mon Dec 13 07:09:05 UTC 2010

Thats correct. The DHCP Server gets both packages:

- The original one from the client as broadcast and
- the copied and tagged one from the relay client (in the switch).

I complained at the manufacturer, that this behavior is not correct. But
the they claimed that it is conform with the standard and that this
configuration would work with their DHCP server.

Do you know if this issue is exactly described somewhere in the RFCs?
Because then I have something to apply some pressure to the manufacturer.

As I understand your last sentence, your relay agents are running on a
router. So therefor the dhcp-server is not in the same subnet. Or do
your relay agents on the APs block the broadcast in any case?

>> "Relay agents are NOT required to monitor or modify client-originated
>> DHCP packets addressed to a server unicast address. This includes the
>> DHCP-REQUEST sent when entering the RENEWING state."
>> DHCPDISCOVER from XX:XX:XX:68:6b:7f via eth0.2: network XXXXXX-Net:
>> no free leases
>> DHCPDISCOVER from XX:XX:XX:68:6b:7f via
> In the piece of RFC you're quoting the key word is unicast.  I believe
> it is quite normal behavior for relay agents to leave unicast packets
> between the client and server unmodified. However, I think that you
> are getting the DHCPDISCOVER both as the original broadcast from the
> client and as a unicast from the relay agent.  I don't believe that's
> normal.  Or maybe it is normal for other products, but at least the
> relay agents I use here which are Motorola wireless APs are not
> behaving that way.
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at
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