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[OpenStack Infra <1837252@xxxxxxxxxxxxxxxxxx>]

Reviewed:  https://review.opendev.org/672834
Committed: https://git.openstack.org/cgit/openstack/os-vif/commit/?id=655c83d706f5de8a8cf23430782e065219297aef
Submitter: Zuul
Branch:    master

commit 655c83d706f5de8a8cf23430782e065219297aef
Author: Sean Mooney <work@xxxxxxxxxxxxxxx>
Date:   Thu Jul 25 22:16:42 2019 +0000

    only disable mac ageing for ovs hybrid plug
    
    The mac ageing configuration on linux bridges is now
    conditional and caller controlled. By default mac ageing
    is unspecified and will use the kernel's default of 300
    seconds. For ovs with hybrid plug we override this to
    0 to prevent packet loss issue during some migration
    edgecases. This change reverts disabling mac ageing
    for the linux bridge plugin which was accidentally
    introduced during the brctl removal via inheriting the
    ovs plugin's default behavior when the bridge create
    code became shared.
    
    Change-Id: I95612352de6cdb47de98eb80c208dd1a74499d41
    Closes-bug: #1837252


** Changed in: os-vif
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1837252

Title:
  IFLA_BR_AGEING_TIME of 0 causes flooding across bridges

Status in neutron:
  Invalid
Status in OpenStack Compute (nova):
  Invalid
Status in os-vif:
  Fix Released
Status in os-vif stein series:
  Confirmed
Status in os-vif trunk series:
  Fix Released
Status in OpenStack Security Advisory:
  Incomplete

Bug description:
  Release: OpenStack Stein
  Driver: LinuxBridge

  Using Stein w/ the LinuxBridge mech driver/agent, we have found that
  traffic is being flooded across bridges. Using tcpdump inside an
  instance, you can see unicast traffic for other instances.

  We have confirmed the macs table shows the aging timer set to 0 for
  permanent entries, and the bridge is NOT learning new MACs:

  root@lab-compute01:~# brctl showmacs brqd0084ac0-f7
  port no	mac addr		is local?	ageing timer
    5	24:be:05:a3:1f:e1	yes		   0.00
    5	24:be:05:a3:1f:e1	yes		   0.00
    1	fe:16:3e:02:62:18	yes		   0.00
    1	fe:16:3e:02:62:18	yes		   0.00
    7	fe:16:3e:07:65:47	yes		   0.00
    7	fe:16:3e:07:65:47	yes		   0.00
    4	fe:16:3e:1d:d6:33	yes		   0.00
    4	fe:16:3e:1d:d6:33	yes		   0.00
    9	fe:16:3e:2b:2f:f0	yes		   0.00
    9	fe:16:3e:2b:2f:f0	yes		   0.00
    8	fe:16:3e:3c:42:64	yes		   0.00
    8	fe:16:3e:3c:42:64	yes		   0.00
   10	fe:16:3e:5c:a6:6c	yes		   0.00
   10	fe:16:3e:5c:a6:6c	yes		   0.00
    2	fe:16:3e:86:9c:dd	yes		   0.00
    2	fe:16:3e:86:9c:dd	yes		   0.00
    6	fe:16:3e:91:9b:45	yes		   0.00
    6	fe:16:3e:91:9b:45	yes		   0.00
   11	fe:16:3e:b3:30:00	yes		   0.00
   11	fe:16:3e:b3:30:00	yes		   0.00
    3	fe:16:3e:dc:c3:3e	yes		   0.00
    3	fe:16:3e:dc:c3:3e	yes		   0.00

  root@lab-compute01:~# bridge fdb show | grep brqd0084ac0-f7
  01:00:5e:00:00:01 dev brqd0084ac0-f7 self permanent
  fe:16:3e:02:62:18 dev tap74af38f9-2e master brqd0084ac0-f7 permanent
  fe:16:3e:02:62:18 dev tap74af38f9-2e vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:86:9c:dd dev tapb00b3c18-b3 master brqd0084ac0-f7 permanent
  fe:16:3e:86:9c:dd dev tapb00b3c18-b3 vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:dc:c3:3e dev tap7284d235-2b master brqd0084ac0-f7 permanent
  fe:16:3e:dc:c3:3e dev tap7284d235-2b vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:1d:d6:33 dev tapbeb9441a-99 vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:1d:d6:33 dev tapbeb9441a-99 master brqd0084ac0-f7 permanent
  24:be:05:a3:1f:e1 dev eno1.102 vlan 1 master brqd0084ac0-f7 permanent
  24:be:05:a3:1f:e1 dev eno1.102 master brqd0084ac0-f7 permanent
  fe:16:3e:91:9b:45 dev tapc8ad2cec-90 master brqd0084ac0-f7 permanent
  fe:16:3e:91:9b:45 dev tapc8ad2cec-90 vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:07:65:47 dev tap86e2c412-24 master brqd0084ac0-f7 permanent
  fe:16:3e:07:65:47 dev tap86e2c412-24 vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:3c:42:64 dev tap37bcb70e-9e master brqd0084ac0-f7 permanent
  fe:16:3e:3c:42:64 dev tap37bcb70e-9e vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:2b:2f:f0 dev tap40f6be7c-2d vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:2b:2f:f0 dev tap40f6be7c-2d master brqd0084ac0-f7 permanent
  fe:16:3e:b3:30:00 dev tap6548bacb-c0 vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:b3:30:00 dev tap6548bacb-c0 master brqd0084ac0-f7 permanent
  fe:16:3e:5c:a6:6c dev tap61107236-1e vlan 1 master brqd0084ac0-f7 permanent
  fe:16:3e:5c:a6:6c dev tap61107236-1e master brqd0084ac0-f7 permanent

  The ageing time for the bridge is set to 0:

  root@lab-compute01:~# brctl showstp brqd0084ac0-f7
  brqd0084ac0-f7
   bridge id		8000.24be05a31fe1
   designated root	8000.24be05a31fe1
   root port		   0			path cost		   0
   max age		  20.00			bridge max age		  20.00
   hello time		   2.00			bridge hello time	   2.00
   forward delay		   0.00			bridge forward delay	   0.00
   ageing time		   0.00
   hello timer		   0.00			tcn timer		   0.00
   topology change timer	   0.00			gc timer		   0.00
   flags

  The default ageing time of 300 is being overridden by the value set
  here:

  Stein: https://github.com/openstack/os-
  vif/blob/stable/stein/os_vif/internal/command/ip/linux/impl_pyroute2.py#L89

  Master: https://github.com/openstack/os-
  vif/blob/master/os_vif/internal/ip/linux/impl_pyroute2.py#L89

  I am not sure of the behavior in OVS environments using the iptables
  firewall, but I have confirmed the 'qbr' bridges also have a ageing
  time of 0 (formerly 300).

  Please let me know if you have any questions.

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