If you decide that you want specific Layer 3 traffic
to take a certain route without participating in IP routing protocols,
you can Configure a Static Route using IPv4
and IPv6 routes.
A default route is a specific static route. If you don’t use
dynamic routing to obtain a default route for your virtual router,
you must configure a static default route. When the virtual router
has an incoming packet and finds no match for the packet’s destination
in its route table, the virtual router sends the packet to the default
route. The default IPv4 route is 0.0.0.0/0; the default IPv6 route
is ::/0. You can configure both an IPv4 and IPv6 default route.
Static routes themselves don’t change or adjust to changes in
network environments, so traffic typically isn’t rerouted if a failure
occurs along the route to a statically defined endpoint. However,
you have options to back up static routes in the event of a problem:
You can configure a static route with a Bidirectional
Forwarding Detection (BFD) profile
so that if a BFD session between the firewall and the BFD peer fails,
the firewall removes the failed static route from the RIB and FIB
tables and uses an alternative route with a lower priority.
By default, static routes have an administrative distance of
10. When the firewall has two or more routes to the same destination,
it uses the route with the lowest administrative distance. By increasing
the administrative distance of a static route to a value higher
than a dynamic route, you can use the static route as a backup route
if the dynamic route is unavailable.
While you’re configuring a static route, you can specify whether
the firewall installs an IPv4 static route in the unicast or multicast
route table (RIB), or both tables, or doesn’t install the route
at all. For example, you could install an IPv4 static route in the
multicast route table only, because you want only multicast traffic
to use that route. This option give you more control over which
route the traffic takes. You can specify whether the firewall installs
an IPv6 static route in the unicast route table or not.