Internet Engineering Task Force Alain Durand Jean-Luc Richier INTERNET-DRAFT IMAG Expire in six months November, 1996 IPv6 network prefix notation 1. Status This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as ``work in progress.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). 2. Abstract This memo propose a text representation of IPv6 network prefixes. 3. Motivation RFC 1884 propose a text representation of IPv6 addresses. IPv6 addresses consist of a network prefix and a local identifier. Routing registry tables use network prefixes. Prefix lengths are important informations for routing algorithms. A compact notation to represent both informations is needed. Durand+Richier [Page 1] DRAFT IPv6 network prefix notation November 1996 4. Notation An IPv6 address is a string of 128 bits that can be represented per [RFC1884] by a string of hex digits separated by ":". This address is composed by two substrings, the network prefix and the local identifier. The boundary between those two substrings is characterized by an integer, the prefix length plen, in the interval [0 - 128]. The proposed method to represent the network prefix is to complement the prefix plen bit string by (128 - plen) bits set to zero. This will make an IPv6 address. Then we represent this address using [RFC1884] to obtain an hex string. The trailing zeros are represented by "::". Eventually, we concatenate the symbol "/" followed by the decimal notation of plen. 5. Examples ::/96 IPv6 prefix for IPv4 compatible addresses fe80::/10 link local prefix 5f06:b500::/32 site prefix 5f06:b500:8158:1a00::/80 local area network prefix 6. Security considerations Security issues are not discussed in this memo. 7. References [RFC1884] Hinden, R., and S. Deering, "IP Version 6 Addressing Architecture", RFC 1884, December 1995. 8. Author address Alain Durand & Jean-Luc Richier Institut d'Informatique et de Mathematiques Appliquees de Grenoble (IMAG), BP 53 38041 Grenoble CEDEX 9 FRANCE Phone : +33 4 76 63 57 03 Fax : +33 4 76 51 49 64 E-Mail: Alain.Durand@imag.fr Jean-Luc Richier@imag.fr Durand+Richier [Page 2]