openvswitch and hostap?

Jouni Malinen j
Sun Nov 23 11:35:55 PST 2014

On Sat, Nov 15, 2014 at 01:28:20AM +0000, James Harper wrote:
> I just threw this patch together. It runs the 'ovs-vsctl port-to-br' command to determine the name of the bridge, falling back to the old bridge detection method if that fails.
> It could be further developed to also add and remove the interface etc, but that's not really the way openvswitch works - interfaces are sticky wrt bridge membership and you don't need to re-add them each boot etc.
> Another option would be to add a config parameter that says "don't do any bridge configuration".

I cannot really claim to be familiar with Open vSwitch and why it would
be used with a WLAN interface, so could you please provide some more
details on what exact fails without this change? Do you configure the
bridge=<ifname> parameter in hostapd.conf? If so, does this fail with
"nl80211: Adding interface .. into bridge .."?

The default behavior in hostapd will likely need to continue to manage
some bridge cases, e.g., due to limitations on WLAN interface not being
allowed to be add to Linux bridge in station mode (i.e., it needs to
happen only after hostapd has been started). While it would be possible
to do something external to manage this, I'm not aware of very good ways
of doing that (especially with dynamic VLAN interface addition adding

I think I'd rather handle Open vSwitch in as simple way as possible and
that may indeed be that not doing anything apart from providing the
bridge ifname in hostapd.conf so that packet sockets can be bound to
receive frames from the correct interface.

Would it be simpler to detect that the configured bridge netdev is Open
VSwitch case rather than the Linux bridge? I'd assume the latter could
at least be identified pretty easily, so the linux_br_add_if() call
could be skipped if brname is not recognized as the Linux bridge.

Jouni Malinen                                            PGP id EFC895FA

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