Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!ames!pasteur!ucbvax!EAST.BERKELEY.EDU!phil
From: phil@EAST.BERKELEY.EDU (Phil Lapsley)
Newsgroups: comp.protocols.tcp-ip
Subject: Who uses directed broadcasts?
Message-ID: <8803191947.AA19431@east.Berkeley.EDU>
Date: 19 Mar 88 19:47:42 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 17

RFC 1009 defines an IP directed broadcast as a datagram with a destination
of an IP (sub)network broadcast address.  The packet is forwarded normally
until it reaches a gateway of the destination (sub)net, at which point the
gateway "bursts" the packet into a media broadcast on the local (sub)net.
RFC 1009 also gives gateways the option of "protecting" their local networks
by dropping directed broadcasts on the floor.

Be default, a 4.3 BSD gateway machine that is final hop of a directed
broadcast packet will accept the packet as if it was destined for itself,
but it will not burst the packet into a media level broadcast.
If DIRECTED_BROADCAST is defined when the 4.3 kernel is made, this bursting
will actually occur.

My question is: what gateway implementations actually use directed
broadcasts in the RFC 1009 sense, and why?

							Phil