L3 router will set its devices link up by default.
For HA routers, the gateway device will be pluged
in all scheduled hosts. When the gateway deivce is
up in backup node, it will send out IPv6 related
packets (MLDv2) according to some kernal config.
This will cause the physical fabric think that the
gateway MAC is now working in the backup node. And
finally the master node L3 traffic will be broken.
This patch sets the backup gateway device link down
by default. When the VRRP sets the master state in
one host, the L3 agent state change procedure will
do link up action for the gateway device.
Conflicts:
neutron/agent/l3/router_info.py
neutron/agent/linux/interface.py
Closes-Bug: #1859832
Change-Id: I8dca2c1a2f8cb467cfb44420f0eea54ca0932b05
(cherry picked from commit c52029c39a)
(cherry picked from commit b9a2968100)
(cherry picked from commit 41e8689234)