Bernat: Tuning the Linux IPv4 route cache
Vincent Bernat has posted a
lengthy description of how the IPv4 routing cache works and how to tune
it for best results. "
Once an entry has been added to the route cache, there are several ways to remove it. Most entries are removed by the garbage collector which will scan the route cache and remove invalid and older entries. It will be triggered when the route cache is full or at regular interval, once a certain threshold has been met." (Thanks to Paul Wise).