[ovs-dev] [PATCH ovn v3 07/10] ovn: Add tunnel_key concept to Bindings table, assign in ovn-northd.

[Ben Pfaff]

On Tue, Apr 28, 2015 at 03:53:03PM -0400, Russell Bryant wrote:
> On 04/24/2015 06:34 PM, Ben Pfaff wrote:
> > When packets travel among nodes in OVN over tunnels, a tunnel key value is
> > needed to convey the logical port to which the packet is destined.  This
> > commit adds a tunnel_key column to the Bindings table and adds code to
> > ovn-northd to assign a unique tunnel_key value to each logical port.
> > 
> > Signed-off-by: Ben Pfaff <blp at nicira.com>
> > ---
> >  ovn/northd/ovn-northd.c |   78 ++++++++++++++++++++++++++++++++++-------------
> >  ovn/ovn-sb.ovsschema    |    6 +++-
> >  ovn/ovn-sb.xml          |    4 +++
> >  3 files changed, 66 insertions(+), 22 deletions(-)
> 
> The code here looks correct and I also tested it.  I was just wondering
> if you could comment on the choice of a 16 bit integer here instead of a
> UUID.  My guess is that it has to do with where this ID will be used in
> a tunnel protocol, but it might be nice to capture that somewhere.

Thanks for the question, I used it to improve the documentation to:

    <column name="tunnel_key">
      A number that represents the logical port in the IDs carried within
      tunnel protocol packets.  (This avoids wasting space for a whole UUID in
      tunneled packets.  It allows OVN to support encapsulations that cannot
      fit an entire UUID in their tunnel keys.)
    </column>

Does that help?