On Tue, Jul 22, 2008 at 10:22:12AM -0400, Warren Togami wrote: > Daniel P. Berrange wrote: > >On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote: > >>https://bugzilla.redhat.com/show_bug.cgi?id=435757 > >>Sometime after F8, something changed where stuff attached to a bridge > >>fails to connect until 15 seconds later. A manual workaround of brctl > >>setfd BRIDGENAME 0.1 makes stuff work immediately. > >> > >>Are there any reasons why don't we do this by default for virbr0 in > >>libvirt? > > > >Because no one has ever suggested it before... > > > >Arguably we should just turn off STP on the virbr0 device. Since it is > >not connected directly to the public LAN[1] there is no risk of network > >loops and thus spanning tree protocol is pointless for virbr0. I wonder > >if somewhere along the lines post F8 GA, STP accidentally got toggled > >from offf by default to on by default on virbr0. Please file a BZ about > >this problem. > > > >Daniel > > > >[1] The only connectivity is outbound, masqueraded / NAT traffic. > > Disabling STP on virbr0 alone is not enough. I just tested it now. STP > enabled or disabled, the default forward delay of 15 seconds makes it > fail for 15 seconds, long enough for most DHCP clients to give up. > > Given this, what should we do? Both disable STP and also reduce the delay? I think I understand what's going on here. - The libvirt 'default' network XML config (aka that for virbr0) does not specify any forward delay or STP setting, so it defaults to delay=0, and STP=on - The libvirt in F8 GA had a bug, where it called 'setfd' instead 'stp' when invoking brctl. - Thus, the default config would result in a bridge with STP off and a delay of 1 second. - A libvirt update fixed the bug in the way we call brctl. Fixing the bug means we now by default create a bridge with STP on and the default kernel delay setting of 15 seconds. - There is a further bug in that if you specify delay=0 in the XML it'll never call 'brctl setfd 0', so you'll be stuck with the 15 second default still. So yes, we need to fix things such that it has STP=on and a tiny (or even zer) forward forward delay again, as per F8 GA behaviour. Can you file a BZ about this problem against libvirt. It impacts F9 and rawhide too Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
