With Cluster Active-Active Routing, the router peers act as a proxy for the other router interface DMACs. But if the two routers try to communicate with each other, packets are not routed correctly on the network.
For two vRouters in a cluster pair with cluster active-active routing enabled, when a switch receives a packet with the destination MAC address of the cluster peer, Netvisor attempts to route the packet. For neighbor discovery, IPv6 routing uses Layer 3 packets instead of Layer 2 for ARP communication.
A vRouter sends a neighbor solicitation packet and the peer vRouter responds with neighbor advertisements containing the destination IP address of the other peer router. On the first peer vRouter, the packet destination MAC matches the second peer MAC and the switch routes this packet back to the CPU port of the same switch. There are two copies of a neighbor advertisement packet on the internal port of the second switch and the Netvisor neighbor advertisement packet does not return to the first switch.
To alleviate this issue, Netvisor adds a host route in the hardware for the link-local IPv6 vRouter peer.Now, when the first cluster peer sends a unicast packet with a link-local destination IPv6 address to the second cluster peer, the first cluster peer has this host route entry which properly routes the packet.