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[Akihiro Motoki <1793354@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

When I change [ovs] of_interface option from ovs-ofctl to native, ping
packets are dropped when restarting ovs-agent.

https://review.openstack.org/#/c/599496/ tries to drop of_interface option.
This means if a deployer uses of_interface "ovs-ofctl" packet drops always occur regardless of their intention.

I am not sure this packet drop is the expected behavior when changing
of_interface option.

I confirmed this behavior with the neutron master (stein).
commit 317cdbf40850964080a0a30d6212a3b536df1caa

Note that the similar packet loss is observed when I changed
of_interface from native to ovs-ofctl, but I think this is less
important.

Steps to reproduce:

(1) Create a server and associate a FIP to the server
(2) Allow PING to the server
(3) Set[ovs] of_interface option to "ovs-ofctl" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "ovs-ofctl"
(4) Start ping to the server like "ping 172.24.4.3 -i 0.2" (172.24.4.3 is the FIP)
(5) Set[ovs] of_interface option to "native" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "native"
(6) Wait for 10 or some seconds (to ensure OVS flows are repopulated)
(7) Stop ping and check if a packet loss occurs

Result:
http://paste.openstack.org/show/730374/
115 packets transmitted, 108 received, 6% packet loss, time 22843ms

** Affects: neutron
     Importance: Undecided
         Status: New


** Tags: ovs

** Tags added: ovs

** Description changed:

  When I change [ovs] of_interface option from ovs-ofctl to native, ping
  packets are dropped when restarting ovs-agent.
  
  https://review.openstack.org/#/c/599496/ tries to drop of_interface option.
  This means if a deployer uses of_interface "ovs-ofctl" packet drops always occur regardless of their intention.
  
  I am not sure this packet drop is the expected behavior when changing
  of_interface option.
  
  I confirmed this behavior with the neutron master (stein).
  commit 317cdbf40850964080a0a30d6212a3b536df1caa
+ 
+ Note that the similar packet loss is observed when I changed
+ of_interface from native to ovs-ofctl, but I think this is less
+ important.
  
  Steps to reproduce:
  
  (1) Create a server and associate a FIP to the server
  (2) Allow PING to the server
  (3) Set[ovs] of_interface option to "ovs-ofctl" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "ovs-ofctl"
  (4) Start ping to the server like "ping 172.24.4.3 -i 0.2" (172.24.4.3 is the FIP)
  (5) Set[ovs] of_interface option to "native" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "native"
  (6) Wait for 10 or some seconds (to ensure OVS flows are repopulated)
  (7) Stop ping and check if a packet loss occurs
  
  Result:
  http://paste.openstack.org/show/730374/
  115 packets transmitted, 108 received, 6% packet loss, time 22843ms

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https://bugs.launchpad.net/bugs/1793354

Title:
  Changing of_interface between native and ovs-ofctl causes packet drops

Status in neutron:
  New

Bug description:
  When I change [ovs] of_interface option from ovs-ofctl to native, ping
  packets are dropped when restarting ovs-agent.

  https://review.openstack.org/#/c/599496/ tries to drop of_interface option.
  This means if a deployer uses of_interface "ovs-ofctl" packet drops always occur regardless of their intention.

  I am not sure this packet drop is the expected behavior when changing
  of_interface option.

  I confirmed this behavior with the neutron master (stein).
  commit 317cdbf40850964080a0a30d6212a3b536df1caa

  Note that the similar packet loss is observed when I changed
  of_interface from native to ovs-ofctl, but I think this is less
  important.

  Steps to reproduce:

  (1) Create a server and associate a FIP to the server
  (2) Allow PING to the server
  (3) Set[ovs] of_interface option to "ovs-ofctl" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "ovs-ofctl"
  (4) Start ping to the server like "ping 172.24.4.3 -i 0.2" (172.24.4.3 is the FIP)
  (5) Set[ovs] of_interface option to "native" and run "sudo service devstack@neutron-agent restart" to ensure of_interface is "native"
  (6) Wait for 10 or some seconds (to ensure OVS flows are repopulated)
  (7) Stop ping and check if a packet loss occurs

  Result:
  http://paste.openstack.org/show/730374/
  115 packets transmitted, 108 received, 6% packet loss, time 22843ms

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