Re: [lwip-users] DHCP discovery

[Baptiste Chaboud-crousaz]

Hi,

I know that a DHCP server tends to always re-assign the same IP address to a MAC address. But it is not compulsory.

Moreover, what happens when several DHCP servers are listening on the network. When my bootloader sends its DHCP discovery (a DHCP server has already offered an IP to my application), would it be possible that another DHCP server offers a new IP to my device? Or all the DHCP servers are aware about all binding IP/MAC?

My application and booyloader use the same MAC address.

Quoting Nicolas Pinault <address@hidden>:

>
> Baptiste Chaboud-crousaz a écrit :
>>
>> Hi all,
>>
>>
>> My firmware is made of a bootloader and an application. Only one is 
>> running at a time but both start by initializing the lwip stack and 
>> launching a DHCP discovery in order to get an IP address.
>>
>> In the case of my application is running an IP address is assigned  
>> to my application. Then, it is possible to jump from my application 
>> to my bootloader. The bootloader will re-inits the lwip stack and  
>> calls DHCP for an IP address: when I sniff my network, I see that  
>> the bootloader sends a DHCP discovery. My problem is that I want  
>> that my bootloader keeps the same IP address that was assigned to  
>> my application. My understanding of the DHCP protocol is that a  
>> DHCP client can propose an IP address to the DHCP server; in this  
>> case, the DHCP client has to send a DHCP request instead of a DHCP  
>> discovery. Does lwip support this feature? How? How should I do to  
>> keep the same IP address for my application and bootloader?
>>
>> Thanks.
>>
>> Baptiste
>>
>>
> Hi,
>
> If your bootloader and your application use the same MAC address, the
> DHCP server should assign the same IP address to your device (device
> running bootloader or application).
>
> Nicolas
>
>>
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