netdev - Re: [Bugme-new] [Bug 14794] New: IP address assigned by DHCP is dropped after ~40 seconds

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Message-ID: <4B2CAA56.8030605@freemail.hu>
Date:	Sat, 19 Dec 2009 11:26:30 +0100
From:	Németh Márton <nm127@...email.hu>
To:	Jarek Poplawski <jarkao2@...il.com>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
	netdev@...r.kernel.org, bugzilla-daemon@...zilla.kernel.org,
	bugme-daemon@...zilla.kernel.org
Subject: Re: [Bugme-new] [Bug 14794] New: IP address assigned by DHCP is dropped
 after ~40 seconds

Jarek Poplawski írta:
> On Fri, Dec 18, 2009 at 05:49:01PM +0100, Németh Márton wrote:
>> Németh Márton worte:
>>> I use KDE, and the KNetworkManager icon is visible on the task bar. When
>>> I unplug the network cable the "disconnected" icon appears. After I plug the
>>> network cable again, a rotating wheel appears. Here comes the difference: *when*
>>> the rotating wheel changes to "connected" state. One case, when the IP address
>>> is kept the "connected" icon appears right after the IP address assigned by
>>> DHCP appears in the ifconfig output. In the wrong case this rotating wheel is
>>> still there for about 60 seconds while the the assigned IP address is dropped
>>> and an IP address like 169.254.123.251 is assigned.
>> I would like to add that with 2.6.32 the IP address is dropped even if I exit
>> the KNetworkManager before unplugging the network cable.
>>
>> I can reproduce the problem without touching the network cable. If I execute
>> (I am running Debian 5.0, kernel 2.6.32):
>>
>> # /etc/init.d/network-manager stop
>>
>> then the network goes down. After this I execute:
>>
>> # /etc/init.d/network-manager start
>>
>> then the network comes up, the IP address assigned by DHCP appears for about a
>> minute then the this IP address is dropped and the address starting with
>> 169.254 is assigned.
> 
> Hmm... currently I'm out of new (wrong ;-) ideas. It seems there is
> some longer break in (mostly multicast) traffic just before releasing
> the DHCP address, according to this wireshark dump. Maybe this network
> manager tries reloading to fix something? (Isn't there nothing strange
> in logs from this network manager, btw?)
>
> You wrote earlier that you can get it working OK with dhclient, so I
> wonder if it's not some userspace (KNetworkManager) incompatibility
> with the new kernel (I mean if it works OK with basic dhcp tools
> started as root). Could you verify that more?

I upgraded the Debian package "network-manager" from 0.6.6-3 to 0.7.2-2.
The problem seems to be solved: the IP address is not dropped in 2.6.32
and in 2.6.31. The conclusion is for me that a user-space program caused
the problem, thanks for the hint.


Regards,

	Márton Németh
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