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From: karn@JUPITER.BELLCORE.COM (Phil R. Karn)
Newsgroups: comp.protocols.tcp-ip
Subject: (none)
Message-ID: <8708172256.AA01038@jupiter.planets>
Date: Mon, 17-Aug-87 18:56:59 EDT
Article-I.D.: jupiter.8708172256.AA01038
Posted: Mon Aug 17 18:56:59 1987
Date-Received: Wed, 19-Aug-87 01:19:32 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
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I'm curious to know if any thought has been given to providing subnet
broadcasting or multicasting in the ARPANET. By this, I mean allowing a host
connected to an ARPANET IMP to send a special 1822 message that is received
by some or all of the other hosts on the ARPANET.  The feature could be
implemented within the PSNs through flooding a la USENET.

Such a feature might be very useful to support IP routing algorithms.  The
gateways could broadcast information to each other much as they do now on
Ethernet (though hopefully something better than RIP would be used!) As I
understand it, this would make the "Core Gateway" notion unnecessary.

It seems to me that if the users of a subnetwork need a broadcast facility,
it should be more efficient to implement it within the subnet.  The only way
the users can simulate it is by sending out "bulk mail", congesting links
with multiple identical messages with different destinations.  With subnet
flooding, however, each link would have to be traversed only once.

Comments?

Phil