[ovs-discuss] LSC does not affect traffic flow

Christopher Seeley christopher.seeley at metova.com
Fri May 31 13:46:32 UTC 2019


I believe that is what Ben was saying. The link state is only for the
internal interface and not the actual bridge itself.

On Tue, May 28, 2019 at 1:24 PM Dan Sneddon <dsneddon at redhat.com> wrote:

> 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
> kernel.
>
> 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:
>
>> OK.
>>
>> 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
>> down?
>> > > 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:
>> >
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>> ]
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>>
>>
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>>
>

-- 
Christopher Seeley
Software Developer
M: (618) 975-6324
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