DVR supports both East/West and North/South routing. While the
SNAT is centralized the DNAT is mostly distributed. There are
certain circumstances where the DNAT might be centralized when
the ports are unbound.
In order to have a well defined behavior and when there are
no external network connectivity available in the compute host,
the DNAT functionality is centralized.
In order to achieve this we are introducing a new agent type
option 'dvr_no_external' to centralize the DNAT.
This new L3 agent type ('dvr_no_external') would only allow the East/West
routing to occur in the compute host and the DNAT or Floating IP will be
configured in the centralized network node.
Change-Id: Ia5d7336e478e0fa5ba62b7ae5ed0c56656116d94
Partial-Bug: #1667877
(cherry picked from commit 9515c771e7)
5524bf8434