For vlan type network, we add a segment match flow
to the openflow security group ingress table. Then
the packets will be recorded in conntrack table, and
the reply packets can be processed properly.
Conflicts:
doc/source/contributor/internals/openvswitch_firewall.rst
Change-Id: Ieded0654d0ad16235ec923b822dcd842bd7735e5
Closes-Bug: #1831534
(cherry picked from commit aa58542e82)