[ovs-discuss] LSC does not affect traffic flow
dsneddon at redhat.com
Tue May 28 18:24:33 UTC 2019
Is this a case of confusion between the switch named br0 and an internal
port on the switch named br0? I have found that many people are confused
about that distinction, especially since ovs-vsctl will create the internal
port automatically with the same name as the bridge.
Shutting down the internal port does not shut down the bridge.
In these steps from the original post:
4) sudo ovs-vsctl add-br br0 -- add-port br0 eth0 -- add-port br0
intern-extern -- set interface intern-extern type=internal
5) sudo ip addr flush dev eth0 && sudo dhclient intern-extern
6) sudo ip link set down dev br0
Step 4 creates bridge br0, and ovs-vsctl automatically creates internal
port br0 on the switch, and exposes that port to the OS networking stack as
a device. Step 6 shuts down that internal port, leaving the bridge still
operational. There are use cases for operating a bridge without an internal
interface, especially when using DPDK to avoid sending traffic to the
Please correct me if I have any of the above wrong, it's still somewhat
confusing to me too, and I've been working with OVS for a long time.
On Thu, May 2, 2019 at 2:09 PM Ben Pfaff <blp at ovn.org> wrote:
> The problem here is conceptual. br0 is just a port on your virtual
> switch. It isn't along the path of your packet. It's like
> disconnecting the Ethernet cable from the management port of a physical
> switch: it doesn't disable traffic from flowing through the other ports.
> On Thu, May 02, 2019 at 03:49:22PM -0500, Christopher Seeley wrote:
> > I am pinging from another server connected to the same switch. I can ping
> > from inside of an LXC container > br0 > eth0 > physical switch > eth0 (on
> > the other server) > br0 (on the other server) > an LXC container (on the
> > other server). I have done this from both servers and it goes through no
> > matter the state of br0 on either of them.
> > On Thu, May 2, 2019 at 3:32 PM Ben Pfaff <blp at ovn.org> wrote:
> > > Please stop dropping the mailing list. I don't help off-list.
> > >
> > > On Thu, May 02, 2019 at 03:15:19PM -0500, Christopher Seeley wrote:
> > > > That is the problem. It's not the wrong traffic, just getting traffic
> > > when
> > > > the bridge is supposed to be down. Does an Open-vSwitch ever come
> > > The
> > > > interface state changes but the bridge state does not.
> > >
> > > You didn't answer my question. How is the ICMP traffic arriving? What
> > > command are you running?
> > >
> > --
> > Christopher Seeley
> > Software Developer
> > M: (618) 975-6324
> > [image:
> > 1472 North Green Mount Road
> > O'Fallon, IL 62269
> discuss mailing list
> discuss at openvswitch.org
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