DVR incompatibility with ARP announcements and VRRP¶
Due to the known issue #1774459 in the upstream implementation, Mirantis does not recommend using Distributed Virtual Routing (DVR) routers in the same networks as load balancers or other applications that utilize the Virtual Router Redundancy Protocol (VRRP) such as Keepalived. The issue prevents the DVR functionality from working correctly with network protocols that rely on the Address Resolution Protocol (ARP) announcements such as VRRP.
The issue occurs when updating permanent ARP entries for
allowed_address_pair IP addresses in DVR routers because DVR performs
the ARP table update through the control plane and does not allow any
ARP entry to leave the node to prevent the router IP/MAC from
contaminating the network.
This results in various network failover mechanisms not functioning in virtual networks that have a distributed virtual router plugged in. For instance, the default back end for MOSK Load Balancing service, represented by OpenStack Octavia with the OpenStack Amphora back end when deployed in the HA mode in a DVR-connected network, is not able to redirect the traffic from a failed active service instance to a standby one without interruption.