[Rdo-list] Fedora 20 / Devstack Networking Issues

Russell Bryant rbryant at redhat.com
Mon Jan 27 14:32:52 UTC 2014

On 01/26/2014 12:01 AM, Perry Myers wrote:
> Ok, I've been chasing down some networking issues along with some other
> folks.  Here's what I'm seeing:
> Starting with a vanilla F20 cloud image running on a F20 host, clone
> devstack into it and run stack.sh.
> First thing is that the RabbitMQ server issue I noted a few weeks ago is
> still intermittently there.  So during the step where rabbitmqctl is run
> to set the password of the rabbit admin user, it might fail and all
> subsequent AMQP communication fails which makes a lot of the nova
> commands in devstack also fail.
> But... if you get past this error (since it is intermittent), then
> devstack seems to complete successfully.  Standard commands like nova
> list, keystone user-list, etc all work fine.
> I did note though that access to Horizon does not work.  I need to
> investigate this further.
> But worse than that is when you run nova boot, the host to guest
> networking (remember this is devstack running in a VM) immediately gets
> disconnected.  This issue is 100% reproducible and multiple users are
> reporting it (tsedovic, eharney, bnemec cc'd)
> I did some investigation when this happens and here's what I found...
> If I do:
> $ brctl delif br100 eth0
> I was immediately able to ping the guest from the host and vice versa.
> If I reattach eth0 back to br100, networking stops again
> Another thing... I notice that on the system br100 does not have an ip
> address, but eth0 does.  I thought when doing bridged networking like
> this, the bridge should have the ip address and the physical iface that
> is attached to the bridge does not get an ip addr.
> So... I tweaked /etc/sysconfig/network-scripts/ifcfg-eth0 to remove the
> dhcp from the bootproto line and I copied ifcfg-eth0 to ifcfg-br100
> allowing it to use bootproto dhcp
> I brought both ifaces down and then brought them both up.  eth0 first
> and br100 second
> This time, br100 got the dhcp address from the host and networking
> worked fine.
> So is this just an issue with how nova is setting up bridges?
> Since this network disconnect didn't happen until nova launched a vm, I
> imagine this isn't a problem with devstack itself, but is likely an
> issue with Nova Networking somehow.
> Russell/DanS, is there any chance that all of the refactoring you did in
> Nova Networking very recently introduce a regression?

I suppose it's possible.  You could try going back to before any of the
nova-network-objects patches went in.  The first one to merge was:

commit a8c73c7d3298589440579d67e0c5638981dd7718
Merge: a1f6e85 aa40c8f
Author: Jenkins <jenkins at review.openstack.org>
Date:   Wed Jan 15 18:38:37 2014 +0000

    Merge "Make nova-network use Service object"

Try going back to before that and see if you get a different result.  If
so, try using "git bisect" to find the offending commit.

Russell Bryant

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