--- 1/draft-ietf-6man-multicast-addr-arch-update-04.txt 2014-06-18 01:14:25.648315824 -0700 +++ 2/draft-ietf-6man-multicast-addr-arch-update-05.txt 2014-06-18 01:14:25.664316207 -0700 @@ -1,24 +1,24 @@ 6man Working Group M. Boucadair Internet-Draft France Telecom Updates: 3306,3956,4291 (if approved) S. Venaas Intended status: Standards Track Cisco -Expires: September 13, 2014 March 12, 2014 +Expires: December 20, 2014 June 18, 2014 Updates to the IPv6 Multicast Addressing Architecture - draft-ietf-6man-multicast-addr-arch-update-04 + draft-ietf-6man-multicast-addr-arch-update-05 Abstract This document updates the IPv6 multicast addressing architecture by - defining the 17-20 reserved bits as generic flag bits. The document + re-defining the reserved bits as generic flag bits. The document provides also some clarifications related to the use of these flag bits. This document updates RFC 3956, RFC 3306 and RFC 4291. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. @@ -31,21 +31,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on September 13, 2014. + This Internet-Draft will expire on December 20, 2014. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -53,109 +53,82 @@ to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Addressing Architecture Update . . . . . . . . . . . . . . . 2 3. Flag Bits: A Recommendation . . . . . . . . . . . . . . . . . 3 - 4. RFC Updates . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4.1. RFC 3306 . . . . . . . . . . . . . . . . . . . . . . . . 4 + 4. RFC Updates . . . . . . . . . . . . . . . . . . . . . . . . . 3 + 4.1. RFC 3306 . . . . . . . . . . . . . . . . . . . . . . . . 3 4.2. RFC 3956 . . . . . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 8. Normative References . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction - This document updates the IPv6 multicast addressing architecture - [RFC4291] by defining the 17-20 reserved bits as generic flag bits - (Section 2). The document provides also some clarifications related - to the use of these flag bits (Section 3). + This document updates the IPv6 addressing architecture [RFC4291] by + re-defining reserved bits as generic flag bits (Section 2). The + document provides also some clarifications related to the use of + these flag bits (Section 3). This document updates [RFC3956], [RFC3306], and [RFC4291]. These updates are logical consequences of the recommendation on the flag bits (Section 3). Textual representation of IPv6 addresses included in the RFC updates follows the recommendation in [RFC5952]. 2. Addressing Architecture Update - Bits 17-20 of a multicast address are defined in [RFC3956] and - [RFC3306] as reserved bits. This document defines these bits as - generic flag bits so that they apply to any multicast address. - Figure 1 and Figure 2 show the updated structure of the addressing - architecture. The first diagram shows the update of the base IPv6 - addressing architecture, and the second shows the update of so-called - Embedded-RP. - - OLD: - | 8 | 4 | 4 | 112 bits | - +--------+----+----+----------------------------------------------+ - |11111111|flgs|scop| group ID | - +--------+----+----+----------------------------------------------+ - - NEW: - | 8 | 4 | 4 | 4 | 108 bits | - +--------+----+----+----------------------------------------------+ - |11111111|ff1 |scop|ff2 | group ID | - +--------+----+----+----+-----------------------------------------+ - - * ff1 refers to "flag field 1" - * ff2 refers to "flag field 2" - * flag bits denote both ff1 and ff2. - - Figure 1: Updated IPv6 Multicast Addressing Architecture + Bits 17-20 of a multicast address, where bit 1 is the most + significant bit, are defined in [RFC3956] and [RFC3306] as reserved + bits. This document defines these bits as generic flag bits so that + they apply to any multicast address. These bits are referred to as + ff2 (flag field 2) while the flgs bits in [RFC4291][RFC3956] are + renamed to ff1 (flag field 1). - OLD (RFC 3956): - | 8 | 4 | 4 | 4 | 4 | 8 | 64 | 32 | - +--------+----+----+----+----+--------+----------------+----------+ - |11111111|flgs|scop|rsvd|RIID| plen | network prefix | group ID | - +--------+----+----+----+----+--------+----------------+----------+ + Within this document, flag bits denote both ff1 and ff2. - NEW: - | 8 | 4 | 4 | 4 | 4 | 8 | 64 | 32 | - +--------+----+----+----+----+--------+----------------+----------+ - |11111111|ff1 |scop|ff2 |RIID| plen | network prefix | group ID | - +--------+----+----+----+----+--------+----------------+----------+ + Defining the bits 17-20 as flags for all IPv6 multicast addresses + allows addresses to be treated in a more uniform and generic way, and + allows for these bits to be defined in the future for different + purposes, irrespective of the specific type of multicast address. - Figure 2: Embedded-RP with Updated IPv6 Multicast Address Arch. + Section 4 specifies the updated structure of the addressing + architecture. Further specification documents may define a meaning for these flag - bits. Defining the bits 17-20 as flags for all IPv6 multicast - addresses allows addresses to be treated in a more uniform and - generic way, and allows for these bits to be defined in the future - for different purposes, irrespective of the specific type of - multicast address. + bits. 3. Flag Bits: A Recommendation Some implementations and specification documents do not treat the flag bits as separate bits but tend to use their combined value as a 4-bit integer. This practice is a hurdle for assigning a meaning to the remaining flag bits. Below are listed some examples for illustration purposes: o the reading of [RFC3306] may lead to conclude that ff3x::/32 is the only allowed SSM IPv6 prefix block. o [RFC3956] states only ff70::/12 applies to Embedded-RP. Particularly, implementations should not treat the fff0::/12 range as Embedded-RP. To avoid such confusion and to unambiguously associate a meaning with - the remaining flags, the following requirement is made + the remaining flags, the following requirement is made: Implementations MUST treat flag bits as separate bits. 4. RFC Updates 4.1. RFC 3306 This document changes Section 4 of [RFC3306] as follows: OLD: @@ -347,24 +320,24 @@ This document does not require any action from IANA. 6. Security Considerations Security considerations discussed in [RFC3956], [RFC3306] and [RFC4291] MUST be taken into account. 7. Acknowledgements - Special thanks to B. Haberman for the discussions prior to the + Special thanks to Brian Haberman for the discussions prior to the publication of this document. - Many thanks to J. Korhonen and T. Jinmei their comments. + Many thanks to Jouni Korhonen and Tatuya Jinmei their review. 8. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 Multicast Addresses", RFC 3306, August 2002. [RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous