1-11 Static Routing ConfigurationWhen configuring a static route, go to these sections for information you are interested in:z Introductionz Configuring a Static Routez Displaying and Maintaining Static Routesz Static Route Configuration ExampleThe term “router” in this document refers to a router in a generic sense or a Layer 3 switch.IntroductionStatic RouteA static route is a manually configured. If a network’s topology is simple, you only need to configurestatic routes for the network to work normally. The proper configuration and usage of static routes canimprove network performance and ensure bandwidth for important network applications.The disadvantage of using static routes is that they cannot adapt to network topology changes. If a faultor a topological change occurs in the network, the routes will be unreachable and the network breaks. Inthis case, the network administrator has to modify the static routes manually.Default RouteIf the destination address of a packet fails to match any entry in the routing table, the packet will bediscarded.After a default route is configured on a router, any packet whose destination IP address matches noentry in the routing table can be forwarded to a designated upstream router.A router selects the default route only when it cannot find any matching entry in the routing table.z If the destination address of a packet fails to match any entry in the routing table, the router selectsthe default route to forward the packet.z If there is no default route and the destination address of the packet fails to match any entry in therouting table, the packet will be discarded and an ICMP packet will be sent to the source to reportthat the destination or the network is unreachable.Default routes can be configured by the network administrator via configuring a default route with bothdestination and mask being 0.0.0.0. The router forwards any packet whose destination address fails tomatch any entry in the routing table to the next hop of the default static route.
