the destination represents. For IP:
- Iff it is a host route, RTF_LOCAL and RTF_BROADCAST indicate local
(belongs to this host) and broadcast addresses, respectively.
- For all routes, RTF_MULTICAST is set if the destination is multicast.
The RTF_BROADCAST flag is used by ip_output() to eliminate a call to
in_broadcast() in a common case; this gives about 1% in our packet-generation
experiments. All three flags might be used (although they aren't now)
to determine whether a packet can be forwarded; a given host route can
represent a forwardable address if:
(rt->rt_flags & (RTF_HOST | RTF_LOCAL | RTF_BROADCAST | RTF_MULTICAST))
== RTF_HOST
Obviously, one still has to do all the work if a host route is not present,
but this code allows one to cache the results of such a lookup if rtalloc1()
is called without masking RTF_PRCLONING.
or ssthresh that we were able to use
tcp_var.h - declare tcpstat entries for above; declare tcp_{send,recv}space
in_rmx.c - fill in the MTU and pipe sizes with the defaults TCP would have
used anyway in the absence of values here
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.
