Hi,

I have tried to use the approach with no success so far.  I needed to tweak
the IP address pool to be compatible with our network.  I hope that isn't a
problem.  In lwipopts.h I have:

// AUTOIP options
#define LWIP_AUTOIP             1
#define LWIP_DHCP_AUTOIP_COOP   1
#define LWIP_DHCP_AUTOIP_COOP_TRIES 3

and the DHCP tries is set to 6 in our application.  I can see our target
board waiting for DHCP and then falling over to a valid address for our
pool.  But I can't ping that address.  Wireshark shows the request for the
local link address, but not much more than that.  Am I missing something?

Bob


On Thu, May 14, 2015 at 2:55 PM, Zach Smith <[email protected]> wrote:

>  Use the auto ip feature of lwip which I believe is the proper way to
> handle this situation. With this feature enabled, after a certain number of
> dhcp timeouts the device will fail over to an “auto ip” address. The auto
> ip address is an address the device chooses for itself in the range
> 169.254.x.x. It will perform a quick check to see if any other device out
> there has the address. If so, it chooses another one and checks again. Upon
> finding a free address it self-configures with that address. dhcp discover
> messages continue to go out at some defined interval and if a dhcp server
> ever responds then the assigned address overwrites the previously assigned
> auto ip address.
>
>
>
> Check out autoip.c (it does all this for you) and the following defines:
>
>
>
> #define LWIP_AUTOIP                                              1
>
> #define LWIP_DHCP_AUTOIP_COOP                  1 //defines auto ip to work
> with dhcp
>
> #define LWIP_DHCP_AUTOIP_COOP_TRIES    6 // controls how many dhcp
> discovers to try before timing out to an auto ip address
>
> #define LWIP_AUTOIP_CREATE_SEED_ADDR     //lets you control the first auto
> ip address the device will try
>
>
>
>
> --
Bob Deschambault
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