Enabling Connectivity Checking in NetworkManager

[Thomas Bechtold]

On Wed, 2012-07-11 at 06:08 +0200, Martin Pitt wrote:
> Mathieu Trudel-Lapierre [2012-07-10 14:41 -0400]:
> > I'd like to enable connectivity checking in NetworkManager. We'd use
> > http://start.ubuntu.com/connectivity-check.html, running the check
> > every 5 minutes starting from the connection being established.
> > start.ubuntu.com has already been in use for a while to verify
> > connectivity from the installer, IIRC.
> 
> That seems rather overzealous to me. Why does it need to re-check so
> often, even after it knows that it is connected to the "real" world
> out there?

because the connection can die. e.g. you use you smartphone as wlan
hotspot and the internet connection of the smartphone dies. 

> It could stop polling until the connection state changes
> then.

if you don't poll, you never know if the connection state changed.

> Several million users pinging the same site every 5 minutes has
> both privacy issues as well as significantly increasing the traffic to
> start.u.c. as well.

maybe we should increase the period when a connection is available (20
minutes?) and decrease the period (10 seconds?) when the connection is
unavailable.

> At the same time, 5 minutes is much too long when you use it for some
> desktop application. After registering in the portal etc. you do not
> want to twiddle your thumbs for 5 minutes until your application is
> finally convinced that it can go on using the interweb now.
> 
> It seems to me that this check would be more appropriate as a D-BUS
> method. It sure needs to be handled async by the application and can
> take a few seconds, but it avoids the 5 minute delay, the constant
> hammering as well as the user count issues?

imho we need both - a dbus method and the possibility for a periodic
check. 

Cheers,

Tom