Author: Charlie

bookmark_borderStatic Routes and Default Routes

Posted on by Charlie

A Static Route is a route that is usually manually configured on routers by the user normally done by adding manual entries into the routing table. This allows for traffic to pass from router to router to reach other networks/destinations. There are other route types such as a dynamic route configured by a routing protocol such as OSPF (Open Shortest Path First) or EIGRP (Enhanced Interior Gateway Routing Protocol). The dynamic routing protocol will typically add these entries into the routing table automatically. By default when a IP address is configured on an interface, two entries will automatically be added into the routing table, this will normally be a local route and a connected route.

The command entered for configuring a static route on a typical Cisco iOS router while in global config mode is:

Router(config)#ip route destination-network subnet-mask next-hop

Instead of specifying the next-hop address for the command, the exit-interface can also be specified instead, for example:

Router(config)#ip route destination-network subnet-mask exit-interface

Or the command can even be combined together such as:

Router(config)#ip route destination-network subnet-mask exit-interface next-hop
  • Destination Network: The network that a packet wants to go to. For example “192.168.1.0”
  • Subnet Mask: The subnet mask of the destination network such as “255.255.255.0”
  • Next-Hop: This is the IP address of the interface on the next router on the way to the destination, or the “next hop” router.
  • Exit Interface: Instead of detailing the IP address of the next router’s interface, you can instead specify the interface from the current router that leads to the next hop router. Such as “g0/0”

A Default Route is a manually configured route entry in the routing table that forwards packets that don’t match any of the specific destination routes in the routing table. Usually also called “the gateway of last resort” on a Cisco router in the routing table and is indicated in the routing table by a *. The default route typically forwards packets towards a interface facing address.

The command for specifying a default route is: 

Router(config)#ip route 0.0.0.0 0.0.0.0 next-hop