[ovs-discuss] SFC using OVN

Ben Pfaff blp at nicira.com
Tue Nov 3 21:01:03 UTC 2015

On Tue, Nov 03, 2015 at 03:45:45PM -0500, Russell Bryant wrote:
> In the meantime, we can be working on how to model this properly in
> OVN_Northbound, as well as trying to work out a reasonable
> implementation based on Geneve.  The modeling in my prototype isn't
> expressive enough.

The model that I proposed in Tokyo was to make redirection through a
chain one of the possible actions for ACLs in the OVN_Northbound
database.  (I'm not claiming this is original or inspired; maybe you had
the same idea.)

Parameters would be needed, and that's probably the harder part.  I
don't know what the universe of reasonable ways to redirect through a
service includes.  I believe we mentioned that redirecting to an IP
address or a MAC address are both expected to be supported.  But that
leaves a lot of questions, such as:

        * Would each service be expected to be able to send the packet
          directly to the next service?  Or would it just bounce it back
          to OVN and OVN would redirect it again?

        * Would the services be able to preserve arbitrary Geneve (or
          NSH) metadata that OVN attaches to packets, so that it can be
          passed back to OVN on exit from the services?

        * Do the services themselves live in logical networks or are
          they identified by IP address (etc.) on a physical network?

Some of these might have obvious answers to people who work in the area
of NFV or SFC.

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