A router forwards data packets based on routing entries in a routing table. These routing entries can be manually configured or calculated using dynamic routing protocols. A static route normally refers to a manually configured route.
In contrast to dynamic routing, static routing is easier to configure, has higher controllability, uses less bandwidth, and does not use CPU resources for route calculation and update analysis. When a network fault occurs or the topology changes, static routes cannot be automatically updated and must be manually reconfigured to adapt to the network change. Therefore, static routes are not suitable for large and complex networks. In addition, it is difficult for network administrators to know the entire network topology. When the network topology or link state changes, a large amount of static routing information of routers needs to be adjusted, which is a laborious.
A static route has five parameters: destination IP address, mask, outbound interface, next-hop IP address, and preference.
The IPv4 destination address of a static route is expressed in dotted decimal notation. The mask of the route can be expressed either in dotted decimal notation or by the mask length. The mask length is the number of consecutive 1s in the mask. For details about the IPv6 destination address and mask of a static route, see IPv6 Addresses in "Basic IPv6 Configuration" in the S2720, S5700, and S6700 V200R019C10 Configuration Guide - IP Service. Setting the destination and mask to all 0s configures a default static route. For details about a default static route, see Default Static Routes.
When configuring a static route, depending on the outbound interface type, you need to specify either an outbound interface or a next-hop IP address.
For point-to-point (P2P) interfaces, specify an outbound interface. This automatically sets the IP address of the remote interface connected to the outbound interface as the next-hop address.
For non-broadcast multiple access (NBMA) interfaces such as Asynchronous Transfer Mode (ATM) interfaces, specify a next-hop IP address. This type of interface supports point-to-multipoint (P2MP) networks, which require mappings between IP addresses and link-layer addresses to be configured. Therefore, during the configuration of static routes, only a next-hop IP address needs to be specified, and no outbound interface needs to be specified.
For broadcast interfaces (such as Ethernet interfaces), specify a next-hop IP address. Ethernet interfaces are broadcast interfaces. If an Ethernet interface is specified as the outbound interface, there will be multiple next hops, and the system will not be able to decide which next hop to use.
Different static routes can have different preference values configured. A smaller preference value indicates a higher priority. Specifying the same preference value for static routes with the same destination implements load balancing among these routes. Conversely, specifying different preference values for static routes with the same destination implements route backup among the routes. For details, see Load Balancing and Route Backup.