[ovs-dev] Does ovs-vsctl add-br br01 really create a bridge just like brctl add-br br01?

黄登辉 huangdenghui at gmail.com
Fri Feb 8 03:18:07 UTC 2013

   Thanks your reply. Yes, I read that manual several times before i sent
the previous post here. This manual tell me that ovs-vsctl  is  a db client
to configure Open vSwitch configuration database maintained by
ovsdb-server. So when you execute ovs-vsctl add-br br01 command, it
actually only store this information in Bridge table of Open vSwitch
configuration database.  Is my understanding right?

   I also read this vlan-configuration-cookbook from
 In this configuration-cookbook, separately create two br0 in two host, by
using command ovs-vsctl add-br br0, then add port eth0, tap0, tap1, after
that, Ping from VM1 to VM3, this should succeed.  here is my confused, how
does it work?  as i describe before, executing command ovs-vsctl add-br
br0,  it actually only store this information into Bridge table.  it
doesn't like executing brctl add-br br0 command, it will invoke  SIOCSIFBR
ioctl to kernel module. ovs-vsctl command should have the similar function
in somewhere? (i can't find it),  otherwise after that steps in
configuration cookbook, ping between VM1 and VM3 can't success.

2013/2/7 Ben Pfaff <blp at nicira.com>

> On Thu, Feb 07, 2013 at 08:40:48PM +0800, ?????? wrote:
> >     Recently, i am reading source code of ovs-vsctl. i get confused. what
> > confused me is ovs-vsctl doesn't send instruction to kernel module, seems
> > that it only store br information into br table. As we know,  brctl
> add-br
> > will send instruction to kernel module by ioctl with flag SIOCSIFBR, and
> > ovs-dpctl add-dp will send instruction  to kernel module by netlink.  So
> my
> > question is that does ovs-vsctl add-br br01 really create a bridge just
> > like brctl add-br br01? If yes, please kindly tell how? Thanks.
> Here is how the ovs-vsctl manpage begins:
>     The ovs-vsctl program configures ovs-vswitchd(8) by providing a
>     high-level interface to its configuration database. See
>     ovs-vswitchd.conf.db(5) for comprehensive documentation of the
>     database schema.
>     ovs-vsctl connects to an ovsdb-server process that maintains an Open
>     vSwitch configuration database.  Using this connection, it queries
>     and possibly applies changes to the database, depending on the
>     supplied commands. Then, if it applied any changes, by default it
>     waits until ovs-vswitchd has finished reconfigur- ing itself before
>     it exits.
> I don't understand how you could possibly interpret that as "ovs-vsctl
> invokes a SIOCSIFBR ioctl".  Can you explain?
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