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[Brian Haley <1507078@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

The code to send gratuitous ARPs changed in Liberty to be simpler
because we started setting the sysctl net.ipv4.ip_nonlocal_bind to 1 in
the root namespace.  It seems like in newer kernels (3.19 or so) that
this sysctl attribute was added to the namespaces, so now that arping
call fails because we are only enabling non-local binds in the root
namespace.

This is an example when run by hand:

$ sudo ip netns exec fip-311e3d4a-00ec-46cc-9928-dbc1a2fe3f9a arping -A -I fg-bb6b6721-78 -c 3 -w 4.5 172.18.128.7
bind: Cannot assign requested address

Failing to get that ARP out can affect connectivity to the floating IP.

In order to support either kernel, the code should change to try setting
it in the namespace, and if it fails, then set it in the root namespace.

This is backport potential to stable/liberty.

** Affects: neutron
     Importance: Undecided
     Assignee: Brian Haley (brian-haley)
         Status: New

** Changed in: neutron
     Assignee: (unassigned) => Brian Haley (brian-haley)

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https://bugs.launchpad.net/bugs/1507078

Title:
  arping for floating IPs fail on newer kernels

Status in neutron:
  New

Bug description:
  The code to send gratuitous ARPs changed in Liberty to be simpler
  because we started setting the sysctl net.ipv4.ip_nonlocal_bind to 1
  in the root namespace.  It seems like in newer kernels (3.19 or so)
  that this sysctl attribute was added to the namespaces, so now that
  arping call fails because we are only enabling non-local binds in the
  root namespace.

  This is an example when run by hand:

  $ sudo ip netns exec fip-311e3d4a-00ec-46cc-9928-dbc1a2fe3f9a arping -A -I fg-bb6b6721-78 -c 3 -w 4.5 172.18.128.7
  bind: Cannot assign requested address

  Failing to get that ARP out can affect connectivity to the floating
  IP.

  In order to support either kernel, the code should change to try
  setting it in the namespace, and if it fails, then set it in the root
  namespace.

  This is backport potential to stable/liberty.

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