Nodes should accept gratuitous ARP

[Denis Meltsaykin]

During failover tests on 6.1 build #432 I've faced a problem with stalled ARP-cache after IP-switchover. Some nodes had old ARP information and could not get connect to MySQL server. After investigation I found that ns_IPaddr2 sends gratuitous ARP replies in order to update neighbors' ARP-caches. But accepting gratuitous ARPs is disabled on each node by default:

root@node-2:~# sysctl -a | grep arp_accept
net.ipv4.conf.all.arp_accept = 0
...
net.ipv4.conf.br-mgmt.arp_accept = 0
net.ipv4.conf.br-mgmt-hapr.arp_accept = 0
...

It is necessary to enable this variables in sysctl.conf setting them to 1
More info: http://www.linuxfoundation.org/collaborate/workgroups/networking/ip-sysctl

[Bogdan Dobrelya (bogdando)]

looks related https://bugs.launchpad.net/fuel/+bug/1310676

[Mike Scherbakov (mihgen)]

Vladimir, please set the priority. We don't want to have triaged bug without priority set.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/184127

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/184127
Committed: https://git.openstack.org/cgit/stackforge/fuel-library/commit/?id=6a79d7dfe4573b69a656a7aee1f1e90fead2a797
Submitter: Jenkins
Branch: master

commit 6a79d7dfe4573b69a656a7aee1f1e90fead2a797
Author: Vladimir Kuklin <email address hidden>
Date: Mon May 18 20:45:59 2015 +0300

    Enable arp_accept for interfaces

    This commit enables arp_accept for all interfaces
    in order for nodes to be able to accept gratuitous
    ARP requests when failover happens.

    Change-Id: I499c7fa671d522854b803ed86907f06412e6e1ef
    Closes-bug: #1456272

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/184234

[OpenStack Infra (hudson-openstack)]

Change abandoned by Dmitry Ilyin (<email address hidden>) on branch: master
Review: https://review.openstack.org/184234

[Alexander Nevenchannyy (anevenchannyy)]

Verified on MOS 6.1 ISO #473
Steps to Verify:
root@node-1:~# sysctl -a | grep arp_accept
net.ipv4.conf.all.arp_accept = 1
net.ipv4.conf.bond0.arp_accept = 1
net.ipv4.conf.br-ex.arp_accept = 1
net.ipv4.conf.br-ex-vrouter.arp_accept = 1
net.ipv4.conf.br-floating.arp_accept = 1
net.ipv4.conf.br-fw-admin.arp_accept = 1
net.ipv4.conf.br-int.arp_accept = 1
net.ipv4.conf.br-mesh.arp_accept = 1
net.ipv4.conf.br-mgmt.arp_accept = 1
net.ipv4.conf.br-mgmt-hapr.arp_accept = 1
net.ipv4.conf.br-mgmt-vrouter.arp_accept = 1
net.ipv4.conf.br-storage.arp_accept = 1
net.ipv4.conf.br-tun.arp_accept = 1
net.ipv4.conf.default.arp_accept = 1
net.ipv4.conf.eth0.arp_accept = 0
net.ipv4.conf.eth0/101.arp_accept = 1
net.ipv4.conf.eth0/102.arp_accept = 1
net.ipv4.conf.eth0/103.arp_accept = 1
net.ipv4.conf.eth1.arp_accept = 1
net.ipv4.conf.hapr-host.arp_accept = 1
net.ipv4.conf.lo.arp_accept = 0
net.ipv4.conf.mgmt-conntrd.arp_accept = 1
net.ipv4.conf.ovs-system.arp_accept = 1
net.ipv4.conf.p_br-floating-0.arp_accept = 1
net.ipv4.conf.vrouter-host.arp_accept = 1