NetworkManager Bridges in Fedora

Dan Williams dcbw at redhat.com
Tue Jan 21 16:07:28 UTC 2014


On Mon, 2014-01-20 at 23:18 -0500, Nico Kadel-Garcia wrote:
> My old notes at
> https://wikis.uit.tufts.edu/confluence/display/TUSKpub/Configure+Pair+Bonding,+VLANs,+and+Bridges+for+KVM+Hypervisor
> were pretty good.
> 
> If you want stable KVM bridging, pair bonding, jumbo frames, or
> consistent network connections of any sort for server  grade
> installations, my urgent advice is to rip NetworkManager out by the
> routes. It provides no useful benefit for a stable server environment,
> and is actively destabilizing because it rewrite and overwrites
> network configurations inconsistently, and in ways that are not
> "idempotent": the same steps executed two times in a row do not
> produce the same results, and only approach consistency thorugh a sort
> of "Newtonian approximation" eventually, but only eventually,
> publishing a vaguely stable configuration.
> 
> Networkmanager is not your friend for stable servers.

We have spent the last few years ensuring this is not the case.  We have
been making tons of changes specifically to ensure stable networking,
eliminate the surprises you may have experienced in the past.  I'd
encourage you to try out these changes in F20 and beyond, and if you
find problems, by all means file bugs and we'll work to fix them.

Dan

> On Sat, Jan 18, 2014 at 11:35 AM, Mateusz Marzantowicz
> <mmarzantowicz at osdf.com.pl> wrote:
> > On 16.01.2014 21:38, Dan Williams wrote:
> >> On Thu, 2014-01-16 at 14:53 -0500, Steve Dickson wrote:
> >>>
> >>> On 16/01/14 14:39, Steve Dickson wrote:
> >>>>
> >>>>
> >>>> On 16/01/14 14:09, Dan Williams wrote:
> >>>>> Also, if wouldn't mind passing along the systemd journal output for
> >>>>> NetworkManager, that might help us figure out what's going on:
> >>>>>
> >>>>> journalctl -b _SYSTEMD_UNIT=NetworkManager.service
> >>>> The log is at:
> >>>>   http://steved.fedorapeople.org/tmp/nm.log
> >>> I bet ya the hang has something to do with these messages:
> >>>
> >>>    <info> (bridge0): IPv4 config waiting until carrier is on
> >>>    <info> (bridge0): IPv6 config waiting until carrier is on
> >>>    <info> Activation (bridge0) Stage 3 of 5 (IP Configure Start) complete.
> >>>
> >>> What carrier is it waiting on? em1 is already up and running...
> >>
> >> So what's happening here is that you two
> >> configurations/connections/profiles that apply to em1: "ifcfg-em1", and
> >> "ifcfg-bridge0_slave_1".  And "ifcfg-em1" is getting chosen, but it's
> >> not a bridge slave configuration, it's just a normal DHCP configuration.
> >>
> >> Since "ifcfg-em1" is not a bridge slave configuration, it never gets
> >> added to the bridge master, and the bridge master sits around waiting
> >> for slaves because it has no carrier which is required for DHCP.
> >>
> >> Persistent fix #1:
> >> edit ifcfg-em1 and change ONBOOT=yes to ONBOOT=no
> >> nmcli con reload
> >> then do "Runtime fix" below
> >>
> >> Persistent fix #2:
> >> rm /etc/sysconfig/network-scripts/ifcfg-em1
> >> nmcli con reload
> >> then do "Runtime fix" below
> >>
> >> (or use nm-connection-editor to delete 'em1' or uncheck "Connect
> >> automatically" from the General tab.)
> >>
> >> Runtime fix (not persistent):
> >> nmcli dev disconnect em1
> >> nmcli con up "bridge0 slave 1"
> >>
> >>
> >> ------
> >> (In old "network" service speak, the runtime operation would be:
> >>
> >> ifdown em1
> >> ifup bridge0_slave_1
> >>
> >> and we still expect these commands to work even when NetworkManager is
> >> managing the interface.)
> >> ------
> >>
> >> Dan
> >>
> >
> > I'm doing this differently and now I don't know which method is
> > recommended by RH/Fedora gurus. I don't use
> > /etc/sysconfig/network-scripts at all but placed all network related
> > configuration in /etc/NetworkManager/system-connections/ directory. Now
> > I'm not sure if I should convert back to using /etc/sysconfig or what?
> > Not to mention that GUI tool is c... and I had to use text editor to
> > configure network bridging.
> >
> >
> >
> > Mateusz Marzantowicz
> > --
> > devel mailing list
> > devel at lists.fedoraproject.org
> > https://admin.fedoraproject.org/mailman/listinfo/devel
> > Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct




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