can't cross address scopes with DVR

[Kevin Benton]

From the devref in https://review.openstack.org/#/c/289794/ there is a limitation with address scopes and DVR. Quote:

Due to the asymmetric route in DVR and the fact that DVR local routers do not
know the information of the floating IPs that don't reside in the local host,
there is a limitation in the DVR multiple hosts scenario. With DVR in
multiple hosts and the destination of traffic which is an internal fixed IP in
a different host, the fixed IP with floating IP associated can't cross scope
to access the internal networks that are in the same address scope of external
network.

[Swaminathan Vasudevan (swaminathan-vasudevan)]

Based on the patch shown below
https://review.openstack.org/#/c/355062/, if the traffic hits the first node through a floatingip, and if the fixed ip is configured on a different node (host), still the traffic will reach the fixed-ip through East-west.

Once the traffic hits the fipnamespace, it will by default forwarded to the router-namespace if the address-scopes match. Once the traffic hits the router-namespace, from there it would take a east-west approach to reach the fixed-ip. Since the ARP entry for that fixed-ip should be populated on all nodes router-namespace.

[Swaminathan Vasudevan (swaminathan-vasudevan)]

Let me know if I am missing something here.

[Brian Haley (brian-haley)]

https://review.openstack.org/#/c/474007/ was a resubmit after a revert, and should fix the issue based on Swami's comment #1.