dhclient and dhcp update require restart?

[Dennis J.]

On 08/27/2009 07:49 PM, David Cantrell wrote:
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> On Wed, 26 Aug 2009, Dariusz J. Garbowski wrote:
>
>> Hi, something that bothers me a bit... More and more system restart
>> requests with each update (even if one doesn't use the package at the
>> time).
>>
>> Is this necessary for dhclient and dhcp update packages to require
>> restart?
>> Wouldn't "service network restart" and "service dhcpd restart" in the
>> install/upgrade
>> scripts do the trick (after checking that the service is actually
>> running)?
>> Ssh used to do that since, well, as far as I remember.
>
> Yes, 'service dhcpd restart' will work fine for dhcpd. For dhclient, it's
> not necessarily as simple as restarting the network service. If you are
> using
> the network service, that will work fine. If you are using NetworkManager,
> you'll need to either restart NetworkManager or have it down the connection
> you're using dhclient on and bring it back up.

Why is a restart of NetworkManager necessary in this case? If dhclient 
reinitializes the interface and gets the old dhcp data then nothing really 
changes and NetworkManager shouldn't have to care. If e.g. der IP changes 
then NetworkManager should detect that and reinitialize the connection info 
on its end (after all the "new" interface might not be connected to 
anything and thus have to be marked as down anyway).

Regards,
   Dennis