Re: SO_REUSEPORT and multicasting

[David Miller <davem@davemloft.net>]

Instead of degenerating this mailing list into a BSD socket
programming class, you may find this informative:

	http://www.unixguide.net/network/socketfaq/4.11.shtml

and it's covered extensively in W. Richard Steven's book, TCP/IP
Illustrated, Volume 2.  It is considered the bible on BSD socket
programming.

Particularly telling is the final paragraph from that web page which
reads:

	Basically SO_REUSEPORT is a BSD'ism that arose when
	multicast was added, evne though it was not used in the
	original Steve Deering code.  I believe some BSD-derived
	systems may also include it.  SO_REUSEPORT lets you bind
	the same address *and* port, but only if all the binders
	have specified it.  But when binding to multicast address
	(its main use), SO_REUSEADDR is considered identical to
	SO_REUSEPORT (p. 731, "TCP/IP Illustrated, Volume 2").
	So for portability of multicast applications, I always
	use SO_REUSEADDR.

I STRONGLY suggest you go read that reference to page 731 in
the Steven book.