expiration timer of anything which would expire later than that. (There
should be a way to call this from ip_sysctl() as well, but there currently
isn't.)
high load:
1) If there ever get to be more than net.inet.ip.rtmaxcache entries
in the cache, in_rtqtimo() will reduce net.inet.ip.rtexpire by
1/3 and do another round, unles net.inet.ip.rtexpire is less than
net.inet.ip.rtminexpire, and never more than once in ten minutes
(rtq_timeout).
2) If net.inet.ip.rtexpire is set to zero, don't bother to cache
anything.
1) Don't clone routes to multicast destinations; there is nothing useful
to be gained in this case.
2) Reduce default expiration timer to one hour. Busy sites will still
likely want to reduce this, but for ordinary users this is a reasonable
value to use.
