Multi-network broadcasting within the Internet (RFC0947)
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2001-Jul-12
Internet Society Requests For Comment (RFCs)
K. Lebowitz: AUTHOR [+2]
1. Status of this Memo
Network Working Group Ken Lebowitz Request for Comments: 947 David Mankins BBN Laboratories
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 . Cronus provides services and communication to processes distributed among a variety of different
Lebowitz Mankins [Page 1]
RFC 947 June 1985 Multi-network Broadcasting within the Internet
types of computer systems. Cronus is built around logical clusters of hosts connected to one or more high-speed LANs. Communication in Cronus is built upon the TCP and UDP protocols. Cronus makes use of broadcasting for dynamically locating resources on other hosts and collecting status information from a collection of servers. Since Cronus's broadcast capabilities are not intended to be limited to the boundaries of a single LAN, we needed to find some way to extend our broadcasting domain to include hosts on distant LANs in order to experiment with clusters that span several physical networks. Cronus predominantly uses...