vswitchd: Deprecate packet buffering in OVS 2.6.

OVS implementation of buffering packets that are sent to the
controller is not compliant with the OpenFlow specifications after
OpenFlow 1.0.  OVS implementation executes the buffered packet against
the actions of the modified or added rule, whereas OpenFlow (since
1.1) specifies that the packet should be matched against the flow
table 0 and processed accordingly.

Rather than fix this behavior, and potentially break OVS users, we
propose to remove the feature altogether, starting in OVS 2.7.  This
patch announces this in 'NEWS' for OVS 2.6, and adds detail to the FAQ
question about backet buffering.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index 280fc1568..143915136 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,15 @@ v2.6.0 - xx xxx xxxx
        packet to size M bytes when outputting to port N.
      * New command OFPGC_ADD_OR_MOD for OFPT_GROUP_MOD message that adds a
        new group or modifies an existing groups
+     * The optional OpenFlow packet buffering feature is deprecated in
+       this release, and will be removed in the next OVS release
+       (2.7).  After the change OVS always sends the 'buffer_id' as
+       0xffffffff in packet-in messages and will send an error
+       response if any other value of this field is included in
+       packet-out and flow mod sent by a controller.  Controllers are
+       already expected to work properly in cases where the switch can
+       not buffer packets, so this change should not affect existing
+       users.
    - Improved OpenFlow version compatibility for actions:
      * New OpenFlow extension to support the "group" action in OpenFlow 1.0.
      * OpenFlow 1.0 "enqueue" action now properly translated to OpenFlow 1.1+.