[systemd-devel] Changing configurations with networkd

[Tom Gundersen]

On Fri, Jul 25, 2014 at 11:19 AM, Michael Olbrich
<m.olbrich at pengutronix.de> wrote:
> Hi,
>
> On Fri, Jul 25, 2014 at 11:00:27AM +0200, Brendan Hide wrote:
>> On 24/07/14 14:05, Marcel Holtmann wrote:
>> >[snip]
>> >>... you already are getting
>> >>assigned the correct IP address at first, and then only later does
>> >>this change. What is causing your DHCP server to send out a different
>> >>IP address later on, I don't know, but it seems unlikely that this is
>> >>anything we can fix in the client.
>> >I have my doubts as well here. Seems like a misconfigured DHCP server.
>>
>> I feel like I'm flogging a dead horse - on the other hand it is
>> twitching just that little bit more than I'm comfortable with. ;)
>>
>> Since Michael specified that he has configured the DHCP lease to
>> last only 10 minutes, it stands to reason that he is getting the new
>> *different* IP address after ten minutes. This time period is highly
>> unusual - but for testing purposes appropriate. So far there is
>> nothing to suggest that the DHCP server is doing anything wrong.
>>
>> Michael, can you confirm the above?
>
> Not quite. When networkd sends a request to renew the address, then I keep
> the same address. However, when networkd is restarted it starts with a
> DHCP discover.
> Most of the time I still get the same address, but occasionally I get a new
> one. I'm not sure what triggers this. It feels like the whole
> discover/ofer/request/ack sequence takes longer for a new address, but I'vv
> not measured this.

If you want to investigate this, the best way is to use wireshark and
listen to DHCP traffic. Should be pretty clear what is going on.

-t