[Bug 1869808] Re: reboot neutron-ovs-agent introduces a short interrupt of vlan traffic

[Trent Lloyd]

SRU proposed for Ubuntu Bionic + Cloud Archive (Queens) for the following 3 bugs:
Bug #1869808 reboot neutron-ovs-agent introduces a short interrupt of vlan traffic
Bug #1887148 Network loop between physical networks with DVR (Fix for fix to Bug #1869808)
Bug #1871850 [L3] existing router resources are partial deleted unexpectedly when MQ is gone

SRU is only required for Bionic + Queens Cloud Archive, all other
releases already have these patches.

==
reboot neutron-ovs-agent introduces a short interrupt of vlan traffic
https://bugs.launchpad.net/neutron/+bug/1869808

pike    1f4f888ad34d54ec968d9c9f9f80c388f3ca0d12        stable/pike [EOL]
queens  131bbc9a53411033cf27664d8f1fd7afc72c57bf        stable/queens [Needed]
rocky   cc48edf85cf66277423b0eb52ae6353f8028d2a6        stable/rocky [EOL]
stein   6dfc35680fcc885d9ad449ca2b39225fb1bca898        14.3.0 [Already done]
train   4f501f405d1c44e00784df8450cbe83129da1ea7        15.2.0 [Already done]
ussuri  88e70a520acaca37db645c3ef1124df8c7d778d5        16.1.0 [Already done]
master  90212b12cdf62e92d811997ebba699cab431d696        17.0.0 [Already done]

==
[L3] existing router resources are partial deleted unexpectedly when MQ is gone
https://bugs.launchpad.net/neutron/+bug/1871850

queens  ec6c98060d78c97edf6382ede977209f007fdb81        stable/queens [Needed]
rocky   5ee377952badd94d08425aab41853916092acd07        stable/rocky [EOL]
stein   71f22834f2240834ca591e27a920f9444bac9689        14.4.0 [Already done]
train   a96ad52c7e57664c63e3675b64718c5a288946fb        15.3.0 [Already done]
ussuri  5eeb98cdb51dc0dadd43128d1d0ed7d497606ded        16.2.0 [Already done]
master  12b9149e20665d80c11f1ef3d2283e1fa6f3b693        17.0.0 [Already done]

==
Network loop between physical networks with DVR (Fix for 1869808)
https://bugs.launchpad.net/neutron/+bug/1887148

pike    00466f41d690ca7c7a918bfd861878ef620bbec9        stable/pike [EOL]
queens  8a173ec29ac1819c3d28c191814cd1402d272bb9        stable/queens [Needed]
rocky   47ec363f5faefd85dfa33223c0087f4444afb5b9        stable/rocky [EOL]
stein   8181c5dbfe799ac6c832ab67b7eab3bcef4098b9        14.3.1 [Already done]
train   17eded13595b18ab60af5256e0f63c57c3702296        15.2.0 [Already done]
ussuri  143fe8ff89ba776618ed6291af9d5e28e4662bdb        16.1.0 [Already done]
master  c1a77ef8b74bb9b5abbc5cb03fb3201383122eb8        17.0.0 [Already done]

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https://bugs.launchpad.net/bugs/1869808

Title:
  reboot neutron-ovs-agent introduces a short interrupt of vlan traffic

Status in Ubuntu Cloud Archive:
  New
Status in Ubuntu Cloud Archive queens series:
  New
Status in Ubuntu Cloud Archive rocky series:
  New
Status in Ubuntu Cloud Archive stein series:
  New
Status in Ubuntu Cloud Archive train series:
  New
Status in Ubuntu Cloud Archive ussuri series:
  New
Status in Ubuntu Cloud Archive victoria series:
  New
Status in neutron:
  Fix Released
Status in neutron package in Ubuntu:
  New
Status in neutron source package in Bionic:
  New
Status in neutron source package in Focal:
  New
Status in neutron source package in Groovy:
  New
Status in neutron source package in Hirsute:
  New

Bug description:
  We are using Openstack Neutron 13.0.6 and it is deployed using
  OpenStack-helm.

  I test ping servers in the same vlan while rebooting neutron-ovs-
  agent. The result shows

  root at mgt01:~# openstack server list
  +--------------------------------------+-----------------+--------+------------------------------------------+------------------------------+-----------+
  | ID                                   | Name            | Status | Networks                                 | Image                        | Flavor    |
  +--------------------------------------+-----------------+--------+------------------------------------------+------------------------------+-----------+
  | 22d55077-b1b5-452e-8eba-cbcd2d1514a8 | test-1-1        | ACTIVE | vlan105=172.31.10.4                      | Cirros 0.4.0 64-bit          | m1.tiny   |
  | 726bc888-7767-44bc-b68a-7a1f3a6babf1 | test-1-2        | ACTIVE | vlan105=172.31.10.18                     | Cirros 0.4.0 64-bit          | m1.tiny   |

  $ ping 172.31.10.4
  PING 172.31.10.4 (172.31.10.4): 56 data bytes
  ......
  64 bytes from 172.31.10.4: seq=59 ttl=64 time=0.465 ms
  64 bytes from 172.31.10.4: seq=60 ttl=64 time=0.510 ms <--------
  64 bytes from 172.31.10.4: seq=61 ttl=64 time=0.446 ms
  64 bytes from 172.31.10.4: seq=63 ttl=64 time=0.744 ms
  64 bytes from 172.31.10.4: seq=64 ttl=64 time=0.477 ms
  64 bytes from 172.31.10.4: seq=65 ttl=64 time=0.441 ms
  64 bytes from 172.31.10.4: seq=66 ttl=64 time=0.376 ms
  64 bytes from 172.31.10.4: seq=67 ttl=64 time=0.481 ms

  As one can see, packet seq 62 is lost, I believe, during rebooting ovs
  agent.

  Right now, I am suspecting
  https://github.com/openstack/neutron/blob/6d619ea7c13e89ec575295f04c63ae316759c50a/neutron/plugins/ml2/drivers/openvswitch/agent/openflow/native/ofswitch.py#L229
  this code is refreshing flow table rules even though it is not
  necessary.

  Because when I dump flows on phys bridge, I can see duration is
  rewinding to 0 which suggests flow has been deleted and created again

  """       duration=secs
                The  time,  in  seconds,  that  the entry has been in the table.
                secs includes as much precision as the switch provides, possibly
                to nanosecond resolution.
  """

  root at compute01:~# ovs-ofctl dump-flows br-floating
  ...
   cookie=0x673522f560f5ca4f, duration=323.852s, table=2, n_packets=1100, n_bytes=103409, 
                              ^------ this value resets
  priority=4,in_port="phy-br-floating",dl_vlan=2 actions=mod_vlan_vid:105,NORMAL
  ...

  IMO, rebooting ovs-agent should not affecting data plane.

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