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Reviewed:  https://review.opendev.org/c/openstack/neutron/+/819900
Committed: https://opendev.org/openstack/neutron/commit/ef7f673098c2a4574365f6f4ed20734f29309f08
Submitter: "Zuul (22348)"
Branch:    master

commit ef7f673098c2a4574365f6f4ed20734f29309f08
Author: Rodolfo Alonso Hernandez <ralonsoh@xxxxxxxxxx>
Date:   Tue Nov 30 16:01:27 2021 +0000

    Do no use "--strict" for OF deletion in TRANSIENT_TABLE
    
    There are two types of OF rules in TRANSIENT_TABLE:
    - With priority 100: these rules match by "in_port", that is a
      unique identifier.
    - With priority 90: these rules match by MAC address and VLAN ID.
      This combination (MAC, VLAN) is unique.
    
    That means when a deleting an OF rule in TRANSIENT_TABLE, it is
    enough to specify the "in_port" or the (MAC, VLAN) tuple. The
    "--strict" parameter, added to also define the priority, is not
    needed.
    
    By removing the "--strict" parameter, these deletion commands can
    be executed synchronously at the end of the OVS deferred context,
    when all the OF rule commands (addition or deletion), are executed
    at the same time. That removes the small window, detected in the
    related bug, when the OF rule set for a port is not complete.
    
    Closes-Bug: #1952770
    Change-Id: I9f5bd8a1404dde3a0aa163ce72aef2961f537676


** Changed in: neutron
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1952770

Title:
  [OVS][FW] Do not delete flows with "--strict" parameter in the OVS FW

Status in neutron:
  Fix Released

Bug description:
  The "--strict" parameter during the OF deletion was introduced to be
  able to define the parameter "priority" in the flow filter. Without "
  --strict" is not possible to filter by "priority". E.g.:

  [root@compute-0 ~]# ovs-ofctl del-flows br-int priority=100,table=60,in_port=144  # error                                                                                                                                                                    
  ovs-ofctl: unknown keyword priority
  [root@compute-0 ~]# ovs-ofctl del-flows --strict br-int priority=100,table=60,in_port=144  # ok

  
  With deferred OF application (that means all flows are written/deleted at the same time, at the end of the deferred context), these strict flow deletion commands are executed before anything else. In some cases we have seen this small window can affect to some kind of traffic. For example UDP traffic is disrupted, the UDP packets arrive to the destination disordered. That could affect some applications.

  Further considerations: with trunk ports, as printed in [1], we can
  see that each subport has its own port ID (for rules with priority
  100) and each own VLAN+MAC (for rules with priority 90).

  [1]https://paste.opendev.org/show/811353/

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