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Appendix B: Network Planning for Dual WAN Ports | 177
ProSafe Dual WAN Gigabit Firewall with SSL & IPsec VPN FVS336Gv2 Reference Manual
Overview of the Planning Process
The areas that require planning when using a firewall that has dual WAN ports include:
Inbound traffic (port forwarding, port triggering)
Outbound traffic (protocol binding)
Virtual private networks (VPNs)
The two WAN ports can be configured on a mutually-exclusive basis to either:
Rollover for increased reliability, or
Balance the load for outgoing traffic.
These two categories of considerations interact to make the planning process more
challenging.
Inbound Traffic
Unrequested incoming traffic can be directed to a PC on your LAN rather than being
discarded. The mechanism for making the IP address public depends on whether the dual
WAN ports are configured to either roll over or balance the loads.
Virtual Private Networks (VPNs)
A virtual private network (VPN) tunnel provides a secure communication channel between
either two gateway VPN firewalls or between a remote PC client and gateway VPN firewall.
As a result, the IP address of at least one of the tunnel end points must be known in advance
in order for the other tunnel end point to establish (or re-establish) the VPN tunnel.
Note: Once the gateway firewall WAN port rolls over, the VPN tunnel
collapses and must be re-established using the new WAN IP
address.
The Roll-over Case for Firewalls With Dual WAN Ports
Rollover for the dual WAN port case is different from the single gateway WAN port case when
specifying the IP address. Only one WAN port is active at a time and when it rolls over, the IP