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| 5.2 |  | Troubleshooting Static Routes |
| 5.2.4 |  | Static route optimization with Ethernet networks |

Configuring static routes without recursive lookups can also be done over multi-access networks like Ethernet. In this instance, using only an exit-interface instead of an intermediate address causes a problem. Because the network is multiaccess, there most likely are multiple devices, receivers, and so on, sharing this network.

Figure shows a network between RouterA and RouterB that is a multiaccess, Fast Ethernet link.

A static route using only an intermediate address could be configured. However, this will cause a recursive routing table lookup. Figure shows both the static route command and its installment in the routing table. When packets need to be routed for 172.16.1.0/14, the recursive route lookup happens first for the 172.16.1.0 network, and then for the intermediate address, with the lookup of 172.16.2.0 network.

In order to avoid the recursive route lookup, the solution is to use both an intermediate address and an exit interface. Figure shows the recommended way to configure a static route in this case, and the routing table entry. When using both the intermediate address and the exit interface, only a single lookup is needed in the routing table lookup process.

The standard rule-of-thumb when configuring static routes is to use an exit interface over point-to-point and exit interfaces with the intermediate address over multiaccess networks. This will avoid the recursive route lookups caused by static routing entries that only contain an intermediate address.