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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 6man Working Group M. Boucadair 3 Internet-Draft France Telecom 4 Updates: 3306,3956,4607,4291 (if approved) S. Venaas 5 Intended status: Standards Track Cisco 6 Expires: October 10, 2013 April 08, 2013 8 Updates to the IPv6 Multicast Addressing Architecture 9 draft-ietf-6man-multicast-addr-arch-update-00 11 Abstract 13 This document updates the IPv6 multicast addressing architecture by 14 defining the 17-20 reserved bits as generic flag bits. The document 15 provides also some clarifications related to the use of these flag 16 bits. 18 This document updates RFC 3956, RFC 3306, RFC 4607 and RFC 4291. 20 Requirements Language 22 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 23 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 24 document are to be interpreted as described in RFC 2119 [RFC2119]. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on October 10, 2013. 43 Copyright Notice 45 Copyright (c) 2013 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Addressing Architecture Update . . . . . . . . . . . . . . . 2 62 3. Clarifications . . . . . . . . . . . . . . . . . . . . . . . 3 63 3.1. Flag Bits . . . . . . . . . . . . . . . . . . . . . . . . 3 64 3.2. IANA Assigned SSM Block . . . . . . . . . . . . . . . . . 4 65 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 66 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 67 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 68 7. Normative References . . . . . . . . . . . . . . . . . . . . 4 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 71 1. Introduction 73 This document updates the IPv6 multicast addressing architecture 74 [RFC4291] by defining the 17-20 reserved bits as generic flag bits 75 (Section 2). The document provides also some clarifications related 76 to the use of these flag bits (Section 3.1) and also about IANA 77 assigned SSM blocks (Section 3.2). 79 This document updates [RFC3956], [RFC3306], [RFC4607] and [RFC4291]. 81 2. Addressing Architecture Update 83 Bits 17-20 of a multicast address are defined in [RFC3956] and 84 [RFC3306] as reserved bits. This document defines these bits as 85 generic flag bits so that they apply to any multicast address. 86 Figure 1 and Figure 2 show the updated structure of the addressing 87 architecture. The first diagram shows the update of the base IPv6 88 addressing architecture, and the second shows the update of so-called 89 Embedded-RP. 91 OLD: 92 | 8 | 4 | 4 | 112 bits | 93 +--------+----+----+----------------------------------------------+ 94 |11111111|flgs|scop| group ID | 95 +--------+----+----+----------------------------------------------+ 96 NEW: 97 | 8 | 4 | 4 | 4 | 108 bits | 98 +--------+----+----+----------------------------------------------+ 99 |11111111|flgs|scop|flgs| group ID | 100 +--------+----+----+----+-----------------------------------------+ 102 Figure 1: Updated IPv6 Multicast Addressing Architecture 104 OLD (RFC3956): 105 | 8 | 4 | 4 | 4 | 4 | 8 | 64 | 32 | 106 +--------+----+----+----+----+--------+----------------+----------+ 107 |11111111|flgs|scop|rsvd|RIID| plen | network prefix | group ID | 108 +--------+----+----+----+----+--------+----------------+----------+ 110 NEW: 111 | 8 | 4 | 4 | 4 | 4 | 8 | 64 | 32 | 112 +--------+----+----+----+----+--------+----------------+----------+ 113 |11111111|flgs|scop|flgs|RIID| plen | network prefix | group ID | 114 +--------+----+----+----+----+--------+----------------+----------+ 116 Figure 2: Embedded-RP with Updated IPv6 Multicast Address Arch. 118 Further specification documents may define a meaning for these flag 119 bits. Defining the bits 17-20 as flags for all IPv6 multicast 120 addresses allows addresses to be treated in a more uniform and 121 generic way, and allows for these bits to be defined in the future 122 for different purposes, irrespective of the specific type of 123 multicast address. 125 3. Clarifications 127 3.1. Flag Bits 129 Some implementations and specification documents do not treat the 130 flag bits as separate bits but tend to use their combined value as a 131 4-bit integer. This practice is a hurdle for assigning a meaning to 132 the remaining flag bits. Below are listed some examples for 133 illustration purposes: 135 o the reading of [RFC4607] may lead to conclude that ff3x::/32 is 136 the only allowed SSM IPv6 prefix block. 138 o [RFC3956] states only ff70::/12 applies to Embedded-RP. 139 Particularly, implementations should not treat the fff0::/12 range 140 as Embedded-RP. 142 To avoid such confusion and to unambiguously associate a meaning with 143 the remaining flags, the following recommendation is made 144 Implementations MUST treat flag bits as separate bits. 146 3.2. IANA Assigned SSM Block 148 Another issue related to SSM is the IANA assigned SSM address block. 149 Per [RFC4607], ff3x::4000:0001 through ff3x::7fff:fff is the block 150 for IANA assignments (http://www.iana.org/assignments/ipv6-multicast- 151 addresses/ipv6-multicast-addresses.xml). However, IANA assignments 152 are permanent addresses and should not have the transient bit set. 153 Quoting from [RFC4607]: 155 "T = 1 indicates a non-permanently-assigned ("transient") 156 multicast address.". 158 4. IANA Considerations 160 This document may require IANA updates. However, at this point it is 161 not clear exactly what these updates may be. 163 5. Security Considerations 165 Security considerations discussed in [RFC3956], [RFC3306], [RFC4607] 166 and [RFC4291] MUST be taken into account. 168 6. Acknowledgements 170 Many thanks to B. Haberman for the discussions prior to the 171 publication of this document. 173 7. Normative References 175 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 176 Requirement Levels", BCP 14, RFC 2119, March 1997. 178 [RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 179 Multicast Addresses", RFC 3306, August 2002. 181 [RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous 182 Point (RP) Address in an IPv6 Multicast Address", RFC 183 3956, November 2004. 185 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 186 Architecture", RFC 4291, February 2006. 188 [RFC4607] Holbrook, H. and B. Cain, "Source-Specific Multicast for 189 IP", RFC 4607, August 2006. 191 Authors' Addresses 193 Mohamed Boucadair 194 France Telecom 195 Rennes 35000 196 France 198 Email: mohamed.boucadair@orange.com 200 Stig Venaas 201 Cisco 202 USA 204 Email: stig@cisco.com