NETGEAR ProSAFE SRX5308 Reference Manual page 45

Configure the Auto-Rollover Mode and Failure Detection Method for
IPv4 Interfaces
To use a redundant ISP link for backup purposes, ensure that the backup WAN interface has
already been configured. Then select the WAN interface that should function as the primary
link for this mode, and configure the WAN failure detection method on the WAN Mode screen
to support auto-rollover.
When the VPN firewall is configured in auto-rollover mode, it uses the selected WAN failure
detection method to detect the status of the primary link connection at regular intervals. For
IPv4 interfaces, the VPN firewall detects link failure in one of the following ways:
• By sending DNS queries to a DNS server
• By sending a ping request to an IP address
From the primary WAN interface, DNS queries or ping requests are sent to the specified IP
address. If replies are not received, after a specified number of retries, the primary WAN
interface is considered down and a rollover to the backup WAN interface occurs. When the
primary WAN interface comes back up, another rollover occurs from the backup WAN
interface back to the primary WAN interface. The WAN failure detection method that you
select applies only to the primary WAN interface, that is, it monitors the primary link only.
Configure Auto-Rollover Mode for IPv4 Interfaces

To configure auto-rollover mode:
1. Select Network Configuration > WAN Settings > WAN Mode. The WAN Mode screen
displays:
Figure 23.
ProSAFE Gigabit Quad WAN SSL VPN Firewall SRX5308
IPv4 and IPv6 Internet and WAN Settings
45