[ovs-discuss] OVS Ports not Available at Boot Time

Nick Couchman Nick.Couchman at seakr.com
Thu Sep 9 16:30:14 UTC 2010

Or, it could be a stupid mistake on my part...actually, it is.  I *assumed* that, when I specified the openvswitch_mod and brcompat_mod in /etc/sysconfig/kernel to load at boot time, that they would be loaded fairly on in the boot process.  Apparently not - apparently they are loaded well after networking starts, etc.  So, the daemons were starting without the modules loaded, which was causing the problem.  I modified the init script to load the modules when the init script runs, and this seems to solve all of the problems.

I believe the second issue, with promisc not be set up correctly, was related to the modules not loading - everything is working fine, now.

Thanks, and sorry for clutter the list with silly questions like this!



>>> On 2010/09/08 at 18:03, Jesse Gross <jesse at nicira.com> wrote: 
> On Wed, Sep 8, 2010 at 1:29 PM, Nick Couchman <Nick.Couchman at seakr.com> wrote:
>> I'm having trouble configuring the OVS startup sequence correctly such that 
> ports are available when the Linux network subsystem attempts to start.  I'm 
> running OpenSuSE 11.3 and OpenvSwitch 1.1.0pre1.  The ovsdb-server, 
> ovs-vswitchd, and ovs-brcompatd daemons start correctly at boot time.  I 
> currently have them starting before Linux attempts to start network devices, 
> as I was under the impression this would allow all of the devices to be 
> created successfully.  However, this does not seem to be the case - although 
> these daemons start correctly, the interfaces (br0, my bridge, and dom0.0, an 
> internal interface I created) are not available when Linux tries to bring up 
> interfaces.  If I shut down all of the daemons and restart them, the 
> interfaces show up correctly.
> Sounds like you have a timing issue, probably introduced by the bridge
> compatibility layer.  What happens if you add a sleep() as a debugging
> measure?  Is it possible to avoid using bridge compatibility and
> directly use the Open vSwitch tools?
>> I've also noticed another problem.  When eth0 is added to br0 (not via Linux 
> bridging, but via open vSwitch) it does not seem to operate in promiscuous 
> mode.  This is problematic for internal interface that I've created, as 
> packets going back to that interface (right now, DHCP responses) don't get 
> put through.  Any hints on how to solve this one?
> Open vSwitch puts the interfaces into promiscuous mode, so I somewhat
> doubt that this is the problem.  My guess is that something is
> dropping the traffic for another reason.  ovs-dpctl dump-flows
> <brname> is a good tool for seeing what Open vSwitch is doing (it
> shows the currently active flows from the last 5 seconds).  Of course
> tcpdump is useful as well and checking that there are no iptables
> rules that might cause problems, etc.

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