Static routes are manually configured entries in the routing table inserted with NIASCFG. For each network or host destination, the network administrator configures the next-hop router and the cost associated with the route.
Routers can use static routes instead of, or in addition to, the routes learned from dynamic routing protocols such as RIP or OSPF. Usually, static routes are configured for destinations reachable through network interfaces that are not using a routing protocol.
Static routes can be active or passive. Although an active static route can be replaced by a lower-cost route learned from a dynamic routing protocol, a passive static route cannot.
In TCP/IP, there are static routes for LANs and WANs.
When the next hop router to the destination is on the same network as one of the TCP/IP LAN interfaces, you should enable LAN Static Routing and configure a static route for the LAN. This route defines the next hop router to which packets to the destination are forwarded. If the router is not the optimal path for a packet, the router can send an ICMP Redirect message to inform the host of a better path. The Router Discovery Protocol can used instead of a static route. this protocol allows a host to dynamically learn the identity of a router on the attached network.
When the next hop router to the destination is reached through a WAN interface, you should configure a static route for the WAN. You do not have to enable LAN Static Routing if your static routes are only for WAN interfaces. Novell Internet Access Server 4.1 routing software uses static routes to provide access to destinations reachable through on-demand WAN connections. You can also use static routes on a permanent WAN connection.
Unlike LAN static route configurations, a WAN static route automatically uses the remote router across the WAN connection as the next hop router.
When a host want s to send data to a remote destination that has a WAN static route configured, the on-demand call is used to establish the WAN connection. As long as data is being transmitted, the call remains connected. If there is no data with only maintenance traffic (for example, RIP updates and ICMP messages) for the entire duration if the Idle Connection Timeout value, the WAN connection is brought down. Because the line is not required to be up all the time, on-demand WAN calls provide cost savings.
There are two types of on-demand calls, routed on-demand and static on-demand.
After the connection is established for a routed on-demand call, RIP is used to update the rest of the network topology. Since RIP updates are considered maintenance traffic, it does not keep the WAN link active.
For static on-demand calls, RIP is disabled automatically at the individual WAN call destination level. Therefore, you can reach only those destinations for which WAN static routes have been configured.
For both types of on-demand calls, be sure that OSPF is not active on the WAN interface. OSPF traffic will bring the link up and keep the link up because OSPF is not considered maintenance traffic.