Re: [lwip-users] FW: Problem with renewing DHCP after link down/up with the new LWIP V2.0.2

[simeon.trifonov]

I replaced the function dhcp_renew() with dhcp_network_changed(). After
power on, the dhcp works fine again (the complete log is attached). The
first strange thing for me is the ARPs that follow. The devices askes who
has IP address 192.168.5.60, but it is his new address... Is that normal?
The other strange thing is that if I disconnect the Ethernet cable and
connect it again (in the same network), all things that follow (after line
12) are not understandable for me. I seems that my device doesn't receive
the frames from the DHCP server. But I have a bad feeling about this. The
Ethernet traffic on my device is tunneled by VARAN interface. I suspect that
after the reconnection, something doesn't work as expected with this
tunneling of the Ethernet frames. However, this is a topic for another
forums. It is surely not a LWIP problem. But I'm really interested how the
ARP that I mentioned above can be explained?!

Simeon

> -----Original Message-----
> From: lwip-users <lwip-users-bounces+simeon.trifonov=amk-
> address@hidden> On Behalf Of address@hidden
> Sent: Friday, March 30, 2018 11:44 AM
> To: Mailing list for lwIP users <address@hidden>
> Subject: Re: [lwip-users] FW: Problem with renewing DHCP after link
> down/up with the new LWIP V2.0.2
> 
> On 30.03.2018 10:40, address@hidden wrote:
> > [..]
> > Now I'm trying to reconnect the Ethernet cable to another network
> > (different address area). The device sends a DHCP request which is a
> > broadcast, but the source is the IP address of the device from the
> > former network and probably as it is expected, it is not answered. I'm
> > wondering how can I handle this situation too? Should I use
> > dhcp_stop(), dhcp_start() to be able to handle all situations by
> reconnecting instead of dhcp_renew()?
> 
> Ehrm, when reconnecting the link, you should now call dhcp_renew() at all.
> Instead, call dhcp_network_changed(). This function does the correct thing
> depending on dhcp state. In your situation, it will call dhcp_reboot(),
which
> should try to renew the lease and if that fails request a new one via
> broadcast.
> 
> Simon
> 
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dhcp_network_changed.pcapng
Description: Binary data