RFC 947 (rfc947) - Page 1 of 5
Multi-network broadcasting within the Internet
Alternative Format: Original Text Document
Network Working Group Ken Lebowitz
Request for Comments: 947 David Mankins
BBN Laboratories
June 1985
Multi-network Broadcasting within the Internet
1. Status of this Memo
This RFC describes the extension of a network's broadcast domain to
include more than one physical network through the use of a broadcast
packet repeater.
The following paper will present the problem of multi-network
broadcasting and our motivation for solving this problem which is in
the context of developing a distributed operating system. We discuss
different solutions to extending a broadcast domain and why we chose
the one that has been implemented. In addition, there is information
on the implementation itself and some notes on its performance.
It is hoped that the ideas presented here will help people in the
Internet who have applications which make use of broadcasting and
have come up against the limitation of only being able to broadcast
within a single network.
The information presented here is accurate as of the date of
publication but specific details, particularly those regarding our
implementation, may change in the future. Distribution of this memo
is unlimited.
2. The Problem
Communication between hosts on separate networks has been addressed
largely through the use of Internet protocols and gateways. One
aspect of internetwork communication that hasn't been solved in the
Internet is extending broadcasting to encompass two or more networks.
Broadcasting is an efficient way to send information to many hosts
while only having to transmit a single packet. Many of the current
local area network (LAN) architectures directly support a broadcast
mechanism. Unfortunately, this broadcast mechanism has a shortcoming
when it is used in networking environments which include multiple
LANs connected by gateways such as in the DARPA Internet. This
shortcoming is that broadcasted packets are only received by hosts on
the physical network on which the packet was broadcast. As a result,
any application which takes advantage of LAN broadcasting can only
broadcast to those hosts on its physical network.
We took advantage of broadcasting in developing the Cronus
Distributed Operating System [1]. Cronus provides services and
communication to processes distributed among a variety of different
Lebowitz & Mankins