Cisco Systems Monitoring a Static or Default Route, Configuration Examples for Static or Default Routes

25-8
Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter25 Configuring Static and Default Routes
Monitoring a Static or Default Route
Monitoring a Static or Default Route
One of the problems with static routes is that there is no inherent mechanism for determining if the route
is up or down. They remain in the routing table even if the next hop gateway becomes unavailable. Static
routes are only removed from the routing table if the associated interface on the ASA goes down.
The static route tracking feature provides a method for tracking the availability of a static route and
installing a backup route if the primary route should fail. For example, you can define a default route to
an ISP gateway and a backup default route to a secondary ISP in case the primary ISP becomes
unavailable.
The ASA implements this feature by associating a static route with a monitoring target that you define,
and monitors the target using ICMP echo requests. If an echo reply is not received within a specified
time period, the object is considered down and the associated route is removed from the routing table. A
previously configured backup route is used in place of the removed route.
When selecting a monitoring target, you need to make sure that it can respond to ICMP echo requests.
The target can be any network object that you choose, but you should consider using the following:
•The ISP gateway (for dual ISP support) address
•The next hop gateway address (if you are concerned about the availability of the gateway)
•A server on the target network, such as a AAA server, that the ASA needs to communicate with
•A persistent network object on the destination network
Note A desktop or notebook computer that may be shut down at night is not a good choice.
You can configure static route tracking for statically defined routes or default routes obtained through
DHCP or PPPoE. You can only enable PPPoE clients on multiple interfaces with route tracking
configured.
To monitor the state of a route in ASDM, in the main ASDM window, perform the following steps:
Step1 Choose Monitoring > Routing > Routes.
In the Routes pane, each row represents one route. You can filter by IPv4 connections, IPv6 connections,
or both. The routing information includes the protocol, the route type, the destination IP address, the
netmask or prefix length, the gateway IP address, the interface through which the route is connected, and
the administrative distance.
Step2 To update the current list, click Refresh.
Configuration Examples for Static or Default Routes
The following example shows how to create a static route that sends all traffic destined for 10.1.1.0/24
to the router 10.1.2.45, which is connected to the inside interface, defines three equal cost static routes
that direct traffic to three different gateways on the outside interface, and adds a default route for
tunneled traffic. The ASA then distributes the traffic among the specified gateways:
Step1 In the main ASDM window, choose Configuration > Device Setup > Routing > Static Routes.