[ovs-discuss] why ovs it does not ask the controller

[Minh Nghiem Gia]

Thanks Ben for your confirmation.
I used wireshark to capture packets on the bridge br0 and physical wlan NIC
(wlan0).
I executed a simple ping from the PC to the gateway. No arp cache so I only
saw arp request for the gatway. when OVS still has normal rule, I saw the
arp packet on both br0 and wlan0. When I deleted all flow rules, I did not
see arp on the bridge but saw arp on the wlan0.

Could you tell me why there is no flow rule, the packet can reach wlan0? I
mean should the OVS drop the packet? Or do arp packets not go through the
switch? And is there any ways to debug/capture this behavior (i.e., OVS
communicate with the system via netlink? The system sends out arp packets?)

Best regards,
Minh.

2015-05-01 23:33 GMT+09:00 Ben Pfaff <blp at nicira.com>:

> On Fri, May 01, 2015 at 03:51:07PM +0900, Minh Nghiem Gia wrote:
> > I have a simple question, however I could not find any way to answer is
> > "why ovs has no rules, it does not ask the controller". In theory, when a
> > new packet comes, if there is no matching found, the switch will ask the
> > controller for actions. In fact, I can see the Packet_in message if I use
> > mininet to connect to a controller on a different PC.
> > What I did is I installed both controller and OVS on the same PC which
> has
> > multiple network interfaces act as ports of OVS. Then I deleted all flow
> > rules on the switch (sudo ovs-ofctl del-flows br0) and executed a ping
> from
> > that PC to the gateway. I think the switch must ask the controller, but
> > there is no OF messages!
>
> OVS should work the same way in the second case as in the first.  OVS
> doesn't know whether the controller is on the same PC or a different
> one.
>
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