libvirt users - Nov 2013 - Re: Problem with bridged network configuration

Hi,

When I initially boot my system, it fails to bring up the network.
Once booted, if I run "systemctl restart network.service", or even
stop,
wait a while, then start, it starts up fine and all is well.

I'm running Fedora 19 (updated).

I followed the instructions on this page to set up a bridged network:
http://wiki.libvirt.org/page/Networking

I note however that I did *not* have any bridge (for NAT use) configured 
initially by default on my system, and followed the directions on this 
page to create it:
https://fedoraproject.org/wiki/Getting_started_with_virtualization

I have disabled the NetworkManager service, and created network 
initscripts for my em1 and br0 interfaces.

I notice from the systemctl status output, that the network failure is 
logged, and only *after* that the br0 interface comes up. So I wonder if 
there is some ordering problem in spite of the fact that I have 
specified DELAY=0 for br0.

I have included output from the following commands:
systemctl status network.service (initially, when failed to come up)
brctl show
ip link
ip address

Also attached are the network initscripts for my em1 and br0 interfaces.

Any guidance would be much appreciated!

Thanks,
    Bob

For the record - I figured this out so am sharing the result for posterity:

The issue was that I didn't follow the instructions literally. Since, 
once booted, my primary NIC name was "em1" I assumed I had to create
an
initscript called ifcfg-em1 rather than ifcfg-eth0 as described in the doc.

Once I renamed that script to ifcfg-eth0 (and changed the DEVICE value 
in the file to match), all is well. It does indeed appear to be a timing 
issue due to the "Predictable Network Interface Names" feature and
when
its NIC name musical chairs dance begins.

I have had more problems due to that one feature than anything else in 
recent memory. It is a misnomer if ever there was one. Even the docs 
related to it are incorrect (for Fedora 19, creating the symlink 
described at 
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
doesn't have the expected result of disabling the feature).

Thanks,
     Bob

On 11/12/2013 10:17 AM, Bob Doolittle wrote:
> Hi,
>
> When I initially boot my system, it fails to bring up the network.
> Once booted, if I run "systemctl restart network.service", or
even
> stop, wait a while, then start, it starts up fine and all is well.
>
> I'm running Fedora 19 (updated).
>
> I followed the instructions on this page to set up a bridged network:
> http://wiki.libvirt.org/page/Networking
>
> I note however that I did *not* have any bridge (for NAT use) 
> configured initially by default on my system, and followed the 
> directions on this page to create it:
> https://fedoraproject.org/wiki/Getting_started_with_virtualization
>
> I have disabled the NetworkManager service, and created network 
> initscripts for my em1 and br0 interfaces.
>
> I notice from the systemctl status output, that the network failure is 
> logged, and only *after* that the br0 interface comes up. So I wonder 
> if there is some ordering problem in spite of the fact that I have 
> specified DELAY=0 for br0.
>
> I have included output from the following commands:
> systemctl status network.service (initially, when failed to come up)
> brctl show
> ip link
> ip address
>
> Also attached are the network initscripts for my em1 and br0 interfaces.
>
> Any guidance would be much appreciated!
>
> Thanks,
>    Bob
>

On 11/12/2013 06:52 PM, Bob Doolittle wrote:
> For the record - I figured this out so am sharing the result for
> posterity:
>
> The issue was that I didn't follow the instructions literally. Since,
> once booted, my primary NIC name was "em1" I assumed I had to
create
> an initscript called ifcfg-em1 rather than ifcfg-eth0 as described in
> the doc.

But you assumed correctly.

>
> Once I renamed that script to ifcfg-eth0 (and changed the DEVICE value
> in the file to match), all is well. It does indeed appear to be a
> timing issue due to the "Predictable Network Interface Names"
feature
> and when its NIC name musical chairs dance begins.

If there is a timing problem, then that is a bug. In udev? systemd?
initscripts? I'm not sure...

Keep in mind, though, that the name of the ifcfg file is definitely
insignificant, and it's possible that the DEVICE and NAME parameters in
the ifcfg file may be ignored at times, as long as there is an HWADDR
and/or uuid to key from.

>
> I have had more problems due to that one feature than anything else in
> recent memory. It is a misnomer if ever there was one. Even the docs
> related to it are incorrect (for Fedora 19, creating the symlink
> described at
>
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
> doesn't have the expected result of disabling the feature).

Are you sure that F19 has that form of netdev naming in the first place?
The non-integrated netdevs on my F19 system have names based on their
slot, e.g. "p4p2", not the type of names specified in the web page you
reference above (e.g. "enp2s0"). Even my F20 system seems a bit up in
the air - what had been called "wlan0" in F17 is now called
"wlp3s0"
(which seems like one of the new names), but an ExpressCard ethernet
plugged into the system is still classified as "p3p1".