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.
to something more recent than the ancient 1.2 release contained in
4.4. This code has the following advantages as compared to
previous versions (culled from the README file for the SunOS release):
- True multicast delivery
- Configurable rate-limiting of forwarded multicast traffic on each
physical interface or tunnel, using a token-bucket limiter.
- Simplistic classification of packets for prioritized dropping.
- Administrative scoping of multicast address ranges.
- Faster detection of hosts leaving groups.
- Support for multicast traceroute (code not yet available).
- Support for RSVP, the Resource Reservation Protocol.
What still needs to be done:
- The multicast forwarder needs testing.
- The multicast routing daemon needs to be ported.
- Network interface drivers need to have the `#ifdef MULTICAST' goop ripped
out of them.
- The IGMP code should probably be bogon-tested.
Some notes about the porting process:
In some cases, the Berkeley people decided to incorporate functionality from
later releases of the multicast code, but then had to do things differently.
As a result, if you look at Deering's patches, and then look at
our code, it is not always obvious whether the patch even applies. Let
the reader beware.
I ran ip_mroute.c through several passes of `unifdef' to get rid of
useless grot, and to permanently enable the RSVP support, which we will
include as standard.
Ported by: Garrett Wollman
Submitted by: Steve Deering and Ajit Thyagarajan (among others)
