Slow startup when network bridge gets no DHCP lease

[Michael]

Binary package hint: netbase

If I create a network bridge including all wired network interfaces as described in README.Debian in the bridge-utils package and boot the system without a LAN cable connected, the system hangs for about 30 seconds during boot. Looking at the networking scripts, I assume that this is the 30 second DHCP timeout in /etc/network/if-pre-up.d/bridge. I have seen that there are a number of similar bugs on Launchpad, but couldn't decide whether or not this one is a duplicate.

System: Kubuntu Feisty Desktop without backports, fully up to date.

If my assumption is correct, then one possible fix would be to split network setup into two parts - one for setting up localhost and one for setting up other network devices. Since on normal desktop setups X11 only depends on having basic networking available (read localhost), the second part could continue in the background while X starts up.

[Michael (michaeljt)]

Shame on me - I took a closer look at the Kubuntu init scripts and saw that the network setup is already split up in the way I suggested above. However, KDM startup still seems to wait for full networking to be up.

I'm not sure how well Kubuntu observes the LSB init script init info - KDM has $remote_fs as a required start. Does this imply that networking must be fully up before /etc/init.d/kdm starts, even if /etc/fstab contains no remote file system mounts?

[Traumflug (mah-jump-ing)]

I don't think this is a KDE issue, as I observe the same on Gnome-Ubuntu. The boot splash screen hangs for some time at about 50% if network is available but DHCP doesn't work. The hang time is about the time the /etc/init.d/network script needs for a timeout.

This is Ubuntu 8.10 AMD64.

[kylea (kylea)]

Same here - takes 60 sec or more to bring up the login window if the wired network is not connected

Ubuntu 8.10 AMD64.

[Stéphane Graber (stgraber)]

Since Ubuntu 11.10, we have proper event based boot, so interfaces should be brought up in the right order, avoiding part of the issue being described here.

However Ubuntu will always wait for all interfaces in /etc/network/interfaces that are marked as auto and exist on the system to be configured or will timeout after 2 minutes. So if your setup is broken and that dhcp client can't succeed, Ubuntu will still be waiting for it. We don't intend on changing that any time soon.