[En-Nut-Discussion] DHCP problems

[Harald Kipp]

Viktor,

this is probably a "missing feature" of the DHCP client
implementation. However, changing the DHCP code alone
won't help. Nut/Net has no provision to shut down its
interface and get it up again without reboot. This would
require major changes. For example, all existing TCP
sessions would become invalid.

Why is rebooting unacceptable?

Harald

At 11:28 16.09.2004 +0200, you wrote:
>Hi,
>
>This problem may be already solved since I am using ethernut v3.4.2, but I 
>can't just upgrade because the program is already in the customer system 
>and I have to find the way to patch it without any major changes.
>
>Set up:
>Ethernut <-> DHCP server.
>
>Problem:
>After reboot the program gets its network configuration using
>NutDhcpIfConfig ("eth0", my_mac, 0);
>and everything works just fine until the DHCP server admin changes the IP 
>address for this MAC to a new one.
>
>For example:
>After reboot
>00:0c:30:d4:86:4e gets 192.168.250.10
>After some time the DHCP server changes the IP address for
>00:0c:30:d4:86:4e to 192.168.250.88.
>After that the Ethernut sends DHCPREQUEST packets to the server but does 
>not see or does not accept the offers. I have checked with Ethereal and 
>OFFER packets _do_ reach the Ethernut. If Ethernut is rebooted it accepts 
>the new IP address and everything is just fine until the next change in 
>the DHCP server configuration. The problem is that it's impossible to 
>restart the system every time there are some changes on the network.
>
>What do you think can be the problem?
>
>I am very thankful for any help, advice or idea.
>
>Regards,
>Viktor