Re: [lwip-users] How to renew DHCP

[address@hidden]

Alain Mouette wrote:
> when using DHCP I call netifapi_dhcp_start() ant poll netif_is_up()
> until the interface is up.
>
> after some long time, if no connection can be made, I want to start DHCP
> again (maybe the cable was diconnected and connected to another
> network), what should be the correct procedure?
>
> Should I jusr call netif_set_down() and start dhcp again? Will DHCP
> renew itself after some timeout?
>    
That depends on the reason for "no connection can be made": if the cable 
is disconnected, you should notify the stack of it using 
netif_set_link_down(). If you have registered a link callback 
(netif_set_link_callback()) before, you can just call dhcp_renew() from 
that callback.

Of course you can always call dhcp_renew() yourself, but the above is 
the recommended (and correctly integrated) way to do it. This might be 
integrated into the stack so that calling netif_set_link_down()/up() 
would be enough.

Calling netif_set_down() and dhcp_start() would work, too, but might 
lead to getting a different address (dhcp_renew() can re-request the old 
address if the server still allows it).

Simon