Constant DHCP requests...

Frank Bulk frnkblk at
Wed Aug 3 01:44:55 UTC 2011

Just for kicks, how does it interact with a Windows 200x DHCP server?  Many
years ago I had an issue with an MPEG-2 encoder that issued DHCP requests
without a request for the subnet mask and gateway.  ISC didn't hand it out
because it wasn't asked for, but Windows 200x servers will.  So a packet
capture of the request may be in order, too.


-----Original Message-----
From: Jeff Justice [mailto:listaccount at] 
Sent: Tuesday, August 02, 2011 11:05 AM
To: frnkblk at; Users of ISC DHCP
Subject: Re: Constant DHCP requests...

It is an Elexol ethernet to relay controller.

We use it to control real-world things over the internet.  Currently our
parking lot lights.


On Aug 1, 2011, at 8:36 PM, Frank Bulk wrote:

> What device is this?  We continue to see issues with Belkin routers in our
> SP network.  A firmware upgrade usually resolves the issue.
> Frank
> -----Original Message-----
> From: at
> [ at] On Behalf Of
> Jeff Justice
> Sent: Sunday, July 31, 2011 7:52 AM
> To: Users of ISC DHCP
> Subject: Constant DHCP requests...
> I know this list is for the ISC DHCP, but I am having a DHCP problem that
> was hoping someone could shed some light on.
> I have a device that hooks to our network that gets its address via DHCP.
> When it is first powered on, it sits there for anywhere from 5 to 20
> without a problem, but then the network light starts flashing constantly.
> I ran a Wireshark trace and discovered that I was getting a constant
> of DHCP Requests from the device followed by the router sending an ACK.
> What led me to ISC's DHCP was that I thought I would install it on a
> on our network, turn off our router's DHCP to see if the problem changed.
> It didn't.  I am still getting flooded with the DHCP request/ack.
> I have had a conversation with the device manufacturer who says they can't
> find any problems with their device.  They sent me a replacement which has
> the same problem.
> This leads me to believe that there is something in the programming of the
> device that isn't handling the DHCP server's response correctly, or there
> a problem with my network or maybe even a switch?
> I'm not sure what steps to take at this point to solve this.  I can't put
> the device in production until I have figured out the cause.
> Any ideas?
> Jeff
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