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

Ben Pfaff blp at nicira.com
Thu Feb 7 15:31:14 UTC 2013


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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