In Static routing routes through a data network are described by fixed paths (statically). These routes are usually entered into the router by the system administrator. An entire network can be configured using static routes but this type of configuration is not fault tolerant. When there is a change in the network or a failure occurs between two statically defined nodes, traffic will not be rerouted. This means that anything that wishes to take an affected path will either have to wait for the failure to be repaired or the static route to be updated by the administrator before restarting its journey. Most requests will time out (ultimately failing) before these repairs can be made. There are, however, times when static routes make sense and can even improve the performance of a network. Some of these include stub networks and default routes.
Static route operations can be divided into these three parts:
* Network administrator configures the route
* Router installs the route in the routing table
* Packets are routed using the static route
Since a static route is manually configured, the administrator must configure the static route on the router using the ip route command.
The default administrative distance when using next-hop address is 1, while the default administrative distance when using the outgoing interface is 0. If an administrative distance other than the default is desired, a value between 0 and 255 is entered after the next-hop or outgoing interface as follows:
cisco1(config)#ip route 172.16.3.0 255.255.255.0 172.16.4.1 130
If the router cannot reach the outgoing interface that is being used in the route, the route will not be installed in the routing table. This means if that interface is down, the route will not be placed in the routing table.
Sometimes static routes are used for backup purposes. A static route can be configured on a router that will only be used when the dynamically learned route has failed. To use a static route in this manner, simply set the administrative distance higher than that of the dynamic routing protocol being used.