Static routing

Static routing is a data communication concept describing one way of configuring path selection of routers in computer networks. It is the type of routing characterized by the absence of communication between routers regarding the current topology of the network.^[1] This is achieved by manually adding routes to the routing table. The opposite of static routing is dynamic routing, sometimes also referred to as adaptive routing.

In these systems, 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 can improve the performance of a network. Some of these include stub networks and default routes.

Example

To configure a static route to network 10.10.20.0/24, pointing to a next-hop router with the IP address of 192.168.100.1, type: (Note that this example is written in the Cisco IOS command line syntax and will only work on certain Cisco routers^[2])

Router> enable
Router# configure terminal
Router(config)# ip route 10.10.20.0 255.255.255.0 192.168.100.1

The other option is to define a static route with reference to the outgoing interface which is connected to the next hop towards the destination network.

Router> enable
Router# configure terminal
Router(config)# ip route 10.10.20.0 255.255.255.0 Serial 0/0

See also

References

1. ^ TCP/IP Tutorial and Technical Overview (IBM RedBooks Series)
2. ^ Cisco IOS Command Reference: ip route