When configuring a static route, another option is to use the exit interface to specify the next-hop address. In older IOS versions, prior to CEF, this method is used to avoid the recursive lookup problem.
In Figure 1, three directly connected static routes are configured on R1 using the exit interface. The routing table for R1 in Figure 2 shows that when a packet is destined for the 192.168.2.0/24 network, R1 looks for a match in the routing table, and finds that it can forward the packet out of its Serial 0/0/0 interface. No other lookups are required.
Notice how the routing table looks different for the route configured with an exit interface than the route configured with a recursive entry.
Configuring a directly connected static route with an exit interface allows the routing table to resolve the exit interface in a single search, instead of two searches. Although the routing table entry indicates “directly connected”, the administrative distance of the static route is still 1. Only a directly connected interface can have an administrative distance of 0.
Note: For point-to-point interfaces, you can use static routes that point to the exit interface or to the next-hop address. For multipoint/broadcast interfaces, it is more suitable to use static routes that point to a next-hop address.
Use the Syntax Checker in Figures 3 and 4 to configure and verify directly connected static routes on R2 and R3.
Although static routes that use only an exit interface on point-to-point networks are common, the use of the default CEF forwarding mechanism makes this practice unnecessary.