Learning OpenStack Networking - Third Edition

Introducing the FIP namespace

Unlike SNAT traffic, traffic through a floating IP with DVR is handled on the individual compute nodes rather than a centralized node. When a floating IP is attached to a virtual machine instance, the L3 agent on the compute node creates a new fip namespace that corresponds to the external network the floating IP belongs to if one doesn't already exist:

Any router namespace on a compute node connected to the same external network shares a single fip namespace and is connected to the namespace using a veth pair. The veth pairs are treated as point-to-point links between the fip namespace and individual qrouter ...