Re: why does NetworkManager: "taking down device" on exit?

[Dan Williams <dcbw redhat com>]

On Thu, 2010-02-25 at 12:58 +0000, Marc Herbert wrote:
> I am using NM 0.7.1, sorry if this has changed or already been discussed.
> 
> Why does NM force all links down when exiting? Does this serve any
> purpose?  This kills basic IPv6 connectivity, something NM is not needed
> for. Actually, this kills any other (less common) protocol you can think of.

NM 0.8.x does not do this for ethernet devices where the connection can
be taken over again on startup.

The main reason is that there's a ton of state when network devices are
up; PPP for 3G connections, wpa_supplicant for wifi and wired 802.1x,
VPN daemons, etc.  It's simply too complex to re-acquire all that state
and verify it when NM starts again.  Plus the fact that we simply
*can't* re-acquire state from daemons like pppd or VPN daemons that
don't implement D-Bus interfaces or other mechanisms of getting state
asnychronously.

But for wired connections that use static IP or DHCP, NM will not take
the device down on exit, and will seamlessly take the device over on
startup as long as the DHCP lease has not expired.  At least with
dhclient, as there's no code to parse the dhcpcd leasefiles at this time
(to match leases up with the device's current IP address and ensure the
least hasn't yet expired).

Dan