Client Relayed from Multiple Relays

[Niall O'Reilly]

On 24 Mar 2017, at 9:28, Alp Eren Kose wrote:

> Hi All,
>
> Does anyone have an idea on this?



> Another related question is; Can you tell
> the DHCP server to give the same IP address to a client for requests coming
> from different relay addresses but in the same subnet/vlan?

  There's no need to tell the DHCP server this; it's a requirement of the
  DHCP protocol.

> Thanks in advance,
> Regards.
>
>
> On Mon, Mar 20, 2017 at 12:56 PM, Alp Eren Kose <alperenkose at gmail.com>
> wrote:
>
>> Hi all,
>>
>> I know this is not something that should be, I mean this is about a
>> mis-configuration on Network but I have a small question, what's the
>> expected behaviour when a client is relayed from multiple Relays, same
>> subnet but different relay IP addresses.

  Expected behaviour is that the DHCP dialog between client and
  server will be duplicated on account of being repeated by each relay.

>> Should it receive a NAK for the requests apart from the first one

  No.  NAK is not used to suppress duplicate requests; it is used to signal
  that a requested address is invalid for the subnet in question.  Sending
  NAK for a duplicate request would invalidate the existing lease for the
  same address.

>> or will the DHCP server give IP addresses for each request?

  The server will normally give the SAME address for each request from the
  same client identified by client identifier or (if no client identifier
  is configured) MAC address.  This, unless the client has failed to renew
  the lease for such a long time that another client has been assigned the
  address in question.

>> Thanks in advance.
>> Regards.
>>

  I hope this helps.

  Niall O'Reilly