The Volume Replication must use the same NIC's and used only for the Volume Replication. For the Auto Failover use another NIC with different subnet or network address and the Virtual IP Address can be on that NIC but with different subnet or network address.
Thanks for the clarificatioin. Another query - when doing replication with failover is it possible to have multiple Virtual IPs for different targets? Or must everything go through the one VIP?