I am considering getting business cable plus a dedicated line from two different ISPs and using the WAN failover feature of our SonicWALL TZ 190 to fail over to the dedicated line if the cable connection goes down. Some servers (Exchange, SharePoint, CRM) need to be accessible externally and so they need public IP addresses. The public IP addresses need to belong to the secondary WAN's address space so that if the primary goes down, the IPs are still accessible (if I'm understanding this correctly).
The SonicWALL's help page says this about WAN failover:
WAN Failover and Load-Balancing applies to outbound-initiated traffic only; it cannot be used to perform inbound load-balancing functions, such as what a content switching or load-balancing appliance provides.
Does anyone know how this affects traffic from an external source directed to the secondary WAN (e.g. mail server)? Does the secondary still receive external->internal traffic when WAN failover is using the active-passive configuration? In other words, does a passive secondary mean that only outbound traffic is limited to the primary until the primary fails, and inbound traffic is allowed on both WANs?
In this scenario should I use the active-passive failover configuration, or one of the others like spillover-based or percentage-based?