Configuring Static and Default Routes
This chapter describes how to configure static and default routes on the ASA, and includes the following sections:
Information About Static and Default Routes
To route traffic to a non-connected host or network, you must define a static route to the host or network or, at a minimum, a default route for any networks to which the ASA is not directly connected; for example, when there is a router between a network and the ASA.
Without a static or default route defined, traffic to non-connected hosts or networks generates the following error message:
%ASA-6-110001: No route to <em>dest_address</em> from <em>source_address </em>
Multiple context mode does not support dynamic routing,
You might want to use static routes in single context mode in the following cases:
•Your networks use a different router discovery protocol from EIGRP, RIP, or OSPF.
•Your network is small and you can easily manage static routes.
•You do not want the traffic or CPU overhead associated with routing protocols.
The simplest option is to configure a default route to send all traffic to an upstream router, relying on the router to route the traffic for you. However, in some cases the default gateway might not be able to reach the destination network, so you must also configure more specific static routes. For example, if the default gateway is outside, then the default route cannot direct traffic to any inside networks that are not directly connected to the ASA.
In transparent firewall mode, for traffic that originates on the ASA and is destined for a non-directly connected network, you need to configure either a default route or static routes so the ASA knows out of which interface to send traffic. Traffic that originates on the ASA might include communications to a syslog server, Websense or N2H2 server, or AAA server. If you have servers that cannot all be reached through a single default route, then you must configure static routes. Additionally, the ASA supports up to three equal cost routes on the same interface for load balancing.Read more…