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Internet subnets (RFC0917)

IP.com Disclosure Number: IPCOM000004328D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2000-Oct-06
Document File: 18 page(s) / 45K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J.C. Mogul: AUTHOR

Abstract

The original view of the Internet universe was a two-level hierarchy: the top level the catenet as a whole, and the level below it a collection of "Internet Networks", each with its own Network Number. (We do not mean that the Internet has a hierarchical topology, but that the interpretation of addresses is hierarchical.)

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Network Working Group Jeffrey Mogul

Request for Comments: 917 Computer Science Department

Stanford University

October 1984

INTERNET SUBNETS

Status Of This Memo

This RFC suggests a proposed protocol for the ARPA-Internet

community, and requests discussion and suggestions for improvements.

Distribution of this memo is unlimited.

Overview

We discuss the utility of "subnets" of Internet networks, which are

logically visible sub-sections of a single Internet network. For

administrative or technical reasons, many organizations have chosen

to divide one Internet network into several subnets, instead of

acquiring a set of Internet network numbers.

We propose procedures for the use of subnets, and discuss approaches

to solving the problems that arise, particularly that of routing.

Acknowledgment

This proposal is the result of discussion with several other people.

J. Noel Chiappa, Chris Kent, and Tim Mann, in particular, provided

important suggestions.

1. Introduction

The original view of the Internet universe was a two-level hierarchy:

the top level the catenet as a whole, and the level below it a

collection of "Internet Networks", each with its own Network Number.

(We do not mean that the Internet has a hierarchical topology, but

that the interpretation of addresses is hierarchical.)

While this view has proved simple and powerful, a number of

organizations have found it inadequate and have added a third level

to the interpretation of Internet addresses. In this view, a given

Internet Network might (or might not) be divided into a collection of

subnets.

The original, two-level, view carries a strong presumption that, to a

host on an Internet network, that network may be viewed as a single

edge; to put it another way, the network may be treated as a "black

box" to which a set of hosts is connected. This is true of the

RFC 917 October 1984

Internet Subnets

ARPANET, because the IMPs mask the use of specific links in that

network. It is also true of most local area network (LAN)

technologies, such as Ethernet or ring networks.

However, this presumption fails in many practical cases, because in

moderately large organizations (e.g., Universities or companies with

more than one building) it is often necessary to use more than one

LAN cable to cover a "local area". For example, at this writing

there are eig...