RFC 2317 (rfc2317) - Page 1 of 10
Classless IN-ADDR
Alternative Format: Original Text Document
Network Working Group H. Eidnes
Request for Comments: 2317 SINTEF RUNIT
BCP: 20 G. de Groot
Category: Best Current Practice Berkeley Software Design, Inc.
P. Vixie
Internet Software Consortium
March 1998
Classless IN-ADDR.ARPA delegation
Status of this Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
2. Introduction
This document describes a way to do IN-ADDR.ARPA delegation on non-
octet boundaries for address spaces covering fewer than 256
addresses. The proposed method should thus remove one of the
objections to subnet on non-octet boundaries but perhaps more
significantly, make it possible to assign IP address space in smaller
chunks than 24-bit prefixes, without losing the ability to delegate
authority for the corresponding IN-ADDR.ARPA mappings. The proposed
method is fully compatible with the original DNS lookup mechanisms
specified in [1], i.e. there is no need to modify the lookup
algorithm used, and there should be no need to modify any software
which does DNS lookups.
The document also discusses some operational considerations to
provide some guidance in implementing this method.
3. Motivation
With the proliferation of classless routing technology, it has become
feasible to assign address space on non-octet boundaries. In case of
a very small organization with only a few hosts, assigning a full
24-bit prefix (what was traditionally referred to as a "class C
network number") often leads to inefficient address space
utilization.
Eidnes, et. al. Best Current Practice