Route Failover - D-Link DFL-1660 User Manual

4.2.3. Route Failover

4.2.3. Route Failover
Overview
NetDefend Firewalls are often deployed in mission-critical locations where availability and
connectivity is crucial. A corporation relying heavily on access to the Internet, for instance, could
have their operations severely disrupted if an Internet connection fails.
As a consequence, it is quite common to have backup Internet connectivity using a secondary
Internet Service Provider (ISP). The connections to the two service providers often use different
access methods to avoid a single point of failure.
To allow for a situation with, for example, multiple ISPs, NetDefendOS provides a Route Failover
capability so that should one route fail, traffic can automatically failover to another, alternate route.
NetDefendOS implements Route Failover through the use of Route Monitoring in which
NetDefendOS monitors the availability of routes and then switches traffic to an alternate route
should the primary, preferred one fail.
Figure 4.2. A Route Failover Scenario for ISP Access
Setting Up Route Failover
Route Monitoring should be enabled on a per-route basis. To enable the Route Failover feature in a
scenario with a preferred and a backup route, the preferred route will have Route Monitoring
enabled, however the backup route does not require it to be enabled since it will usually have no
route to failover to. For a route with Route Monitoring enabled, one of two Route Monitoring
methods must be chosen:
Interface Link Status
Tip: Understanding output from the routes command
For detailed information about the output of the CLI routes command. Please see the
CLI Reference Guide.
NetDefendOS will monitor the link status of the interface
specified in the route. As long as the interface is up, the route is
diagnosed as healthy. This method is appropriate for monitoring
that the interface is physically attached and that the cabling is
working as expected. As any changes to the link status are
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Chapter 4. Routing