ProSafe Gigabit Quad WAN SSL VPN Firewall SRX5308 Reference Manual
2-18 Connecting the VPN Firewall to the Internet
v1.0, April 2010
Configuring the Auto-Rollover Mode and Failure Detection
Method
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 will act 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. Link
failure is detected in one of the following ways:
• By sending DNS queries to a DNS server
• By sending a ping request to an IP address
• None (no failure detection is performed)
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 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.
Configuring Auto-Rollover Mode
To configure auto-rollover mode:
1. Select Network Configuration > WAN Settings from the menu.
2. Click the WAN Mode tab. The WAN Mode screen displays (see Figure 2-13 on page 2-19).
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