[ovs-dev] [patch_v4] ovn: Add local router support (RFC)

[Ben Pfaff]

On Tue, May 31, 2016 at 09:37:10AM -0700, Darrell Ball wrote:
> This patch adds local router support.  The CMS provides a hint for
> a NB distributed logical router as to which logical switches the
> logical router services; the CMS always knows this information.  A
> new external ID tentatively named local-router-lss is used, which is
> a list of NB logical switch UUIDs associated with a logical router.
> 
> This association is converted by northd into SB database format also
> using an external ID, local-router-lss, but storing logical switch datapath
> tunnel keys.
> 
> During lflow processing the above southbound association is queried to
> allow only processing southbound logical flows that are needed on a given
> HV. Two hash tables are used to keep track of which logical router data paths
> are needed locally and which are already known to be not needed.
> 
> Signed-off-by: Darrell Ball <dlu998 at gmail.com>

I don't understand why the CMS needs to separately provide this
information to the hypervisors.  I think that a hypervisor can start
from the VIFs that it hosts, then follow patch ports from the logical
switches that those VIFs are on to arrive at the logical routers that
the hypervisor hosts, and so on recursively.