[ovs-dev] Agenda for IRC neeting for 8/13 (Nithin Raju)

[Ben Pfaff]

On Fri, Aug 22, 2014 at 03:24:47PM +0000, Samuel Ghinet wrote:
> What I was testing against was ovs 1.9.3 and ovs 1.11

OVS 1.9.3 needed a trip to userspace for every new microflow.  But OVS
1.11 introduced megaflows, so that in many cases that is no longer
necessary.

> The fact is that, even for the latest version of ovs, there is no
> kernel port type = NORMAL or FLOOD (see enum
> ovs_vport_type). OFPP_NORMAL and OFPP_FLOOD exist in userspace only.
> Therefore, you cannot have exactly the same handling of a flow that
> says "actions=normal" as one that says "actions=output:1".

I'm really quite puzzled why you think "flood" is tricky or special.  It
is trivial: the datapath actions merely list all of the ports in the
bridge except for the input port.  If ports are added or deleted,
userspace revises the actions.

For "normal", the datapath actions direct the packet to the port that
has been learned via MAC learning, or flood the packet (as above) if the
destination MAC hasn't been learned.  When the MAC learning entry
changes or appears or disappears, userspace revises the actions.  The
need for MAC learning makes the process of deciding where packets go a
little more complicated in userspace, but it doesn't require more trips
to userspace.