Routers in a VRRP group communicate among one another over a dedicated HA network. An HA router is automatically configured with an interface prefixed with that is only used for this communication.
The first time an HA router is created in a project, Neutron configures a network and subnet using the CIDR 169.254.192.0/18. The network type used is based on the default project network type. Only one HA network is created per project, and it is used by all HA routers that are created by that project. If all HA routers in a project are deleted, the HA network will remain and will be reused for all other HA routers that get created by the project in the future.
Networks created by Neutron for VRRP communication between routers are not actually assigned to projects. As a result, these networks are hidden from regular users in the CLI and GUI. The name of the network reflects the associated project, however, and is used by the L3 agent for identification purposes. Under normal conditions, an HA network should remain hidden and not be modified by users or administrators.