Learning OpenStack Networking - Third Edition

Using proxy ARP

Floating IPs are configured on the rfp interface within the qrouter namespace, but are not directly reachable from the gateway of the external network, since the fip namespace sits between the qrouter namespace and the external network.

To allow for the routing of traffic through the fip namespace back to the qrouter namespace, Neutron relies on the use of proxy arp. By automatically enabling proxy arp on the fg interface, the fip namespace is able to respond to ARP requests for the floating IP, on behalf of the floating IP, from the upstream gateway device.

When traffic is routed from the gateway device to the fip namespace, the routing table is consulted and traffic is routed to the respective qrouter namespace:

The following ...