This read-write field sets, in seconds, how long an entry in the IP Fast Forwarding Table can remain idle before it is aged out and removed from the cache. An administrator tunes this to balance cache freshness against churn, since too short wastes CPU re-learning active flows and too long lets stale entries linger and consume cache space. For example, lowering rlInetFftAgingTimeout on a network with many short-lived flows frees up FFT cache slots for new traffic faster.