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| 5.2 |  | Troubleshooting Static Routes |
| 5.2.5 |  | Recurring static route installation and deletion |

The static routing process will check the routing table every minute to install or remove any static routes. There are circumstances where this can lead to a recurrence of route installation and deletion.

An interesting but problematic condition can occur when the installation of a new static route affects the resolvability of its own intermediate address.

At first, the 20.1.0.0/16 route is installed in the routing table and the intermediate address of 20.2.0.2 is resolved using the default route. However, the classful routing table lookup process does not allow a default route to resolve intermediate addresses. After 60 seconds, the next time the static route process is scheduled to run, it will remove this route. In another 60 seconds, the static route process will install the static route back into the routing table, again using the default route to resolve the intermediate address of 20.2.0.2.

This process of adding and deleting this static route is repeated every 60 seconds. Notice the times in the debug output. This is also a demonstration of how the static route process is implemented every 60 seconds.

This situation can create even more instability if there are other static routes resolved by this route. One solution is to always configure static routes to use exit interfaces instead of intermediate addresses wherever possible.