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[James Page <james.page@xxxxxxxxxx>]

** Also affects: openvswitch (Ubuntu Artful)
   Importance: Undecided
       Status: New

** Also affects: openvswitch (Ubuntu Bionic)
   Importance: Critical
       Status: Confirmed

** Changed in: openvswitch (Ubuntu Artful)
     Assignee: (unassigned) => James Page (james-page)

** Changed in: openvswitch (Ubuntu Bionic)
     Assignee: (unassigned) => James Page (james-page)

** Changed in: openvswitch (Ubuntu Artful)
   Importance: Undecided => Critical

** Changed in: openvswitch (Ubuntu Artful)
       Status: New => In Progress

** Changed in: openvswitch (Ubuntu Bionic)
       Status: Confirmed => In Progress

** Also affects: cloud-archive
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/queens
   Importance: Undecided
       Status: New

** Also affects: cloud-archive/pike
   Importance: Undecided
       Status: New

** Changed in: cloud-archive/pike
       Status: New => In Progress

** Changed in: cloud-archive/queens
       Status: New => In Progress

** Changed in: cloud-archive/queens
   Importance: Undecided => High

** Changed in: cloud-archive/pike
   Importance: Undecided => Critical

** Changed in: cloud-archive/pike
     Assignee: (unassigned) => James Page (james-page)

** Changed in: openvswitch (Ubuntu Bionic)
   Importance: Critical => High

** Changed in: cloud-archive/queens
     Assignee: (unassigned) => James Page (james-page)

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Engineering Team, which is subscribed to neutron.
https://bugs.launchpad.net/bugs/1742505

Title:
  gre_sys set to default 1472 when using path_mtu > 1500 with ovs 2.8.x

Status in Ubuntu Cloud Archive:
  In Progress
Status in Ubuntu Cloud Archive pike series:
  In Progress
Status in Ubuntu Cloud Archive queens series:
  In Progress
Status in neutron:
  Invalid
Status in openvswitch package in Ubuntu:
  In Progress
Status in openvswitch source package in Artful:
  In Progress
Status in openvswitch source package in Bionic:
  In Progress

Bug description:
  Setup:
  Pike neutron 11.0.2-0ubuntu1.1~cloud0
  OVS 2.8.0
  Jumbo frames setttings per: https://docs.openstack.org/mitaka/networking-guide/config-mtu.html
  global_physnet_mtu = 9000
  path_mtu = 9000

  Symptoms:
  gre_sys MTU is 1472
  Instances with MTUs > 1500 fail to communicate across GRE

  Temporary Workaround:
  ifconfig gre_sys MTU 9000
  Note: When ovs rebuilds tunnels, such as on a restart, gre_sys MTU is set back to default 1472.

  Note: downgrading from OVS 2.8.0 to 2.6.1 resolves the issue.

  Previous behavior:
  With Ocata or Pike and OVS 2.6.x
  gre_sys MTU defaults to 65490
  It remains at 65490 through restarts.

  This may be related to some combination of the following changes in OVS which seem to imply MTUs must be set in the ovs database for tunnel interfaces and patches:
  https://github.com/openvswitch/ovs/commit/8c319e8b73032e06c7dd1832b3b31f8a1189dcd1
  https://github.com/openvswitch/ovs/commit/3a414a0a4f1901ba015ec80b917b9fb206f3c74f
  https://github.com/openvswitch/ovs/blob/6355db7f447c8e83efbd4971cca9265f5e0c8531/datapath/vport-internal_dev.c#L186

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