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Unicast-Prefix-based IPv6 Multicast Addresses
draft-ietf-ipngwg-uni-based-mcast-02

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 3306.
Authors Brian Haberman , Brian Haberman , Dave Thaler
Last updated 2015-10-14 (Latest revision 2001-06-27)
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Formats
Additional resources Mailing list discussion
Stream WG state (None)
Document shepherd (None)
IESG IESG state Became RFC 3306 (Proposed Standard)
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(None)
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Allison J. Mankin
IESG note
Send notices to <mrw@windriver.com>
draft-ietf-ipngwg-uni-based-mcast-02
IPNGWG Working Group                                        B. Haberman 
   Internet Draft                                          Nortel Networks 
   draft-ietf-ipngwg-uni-based-mcast-02.txt                      D. Thaler 
   June 2001                                                     Microsoft 
   Expires December 2001                                                   
 
 
             Unicast-Prefix-based IPv6 Multicast Addresses 
 
    
Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026 [RFC 2026].  
    
   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."  
    
   The list of current Internet-Drafts can be accessed at 
   http://www.ietf.org/ietf/1id-abstracts.txt. 
     
   The list of Internet-Draft Shadow Directories can be accessed at 
   http://www.ietf.org/shadow.html. 
     
     
Abstract 
    
   This specification defines an extension to the multicast addressing 
   architecture of the IP Version 6 protocol.  The extension presented 
   in this document allows for unicast-prefix-based allocation of 
   multicast addresses.  By delegating multicast addresses at the same 
   time as unicast prefixes, network operators will be able to identify 
   their multicast addresses without needing to run an inter-domain 
   allocation protocol. 
    
    
Table of Contents 
    
   Status of this Memo................................................1 
   Abstract...........................................................1 
   1. Introduction....................................................2 
   2. Terminology.....................................................2 
   3. Multicast Address Format........................................2 
   4. Source-Specific Multicast Addresses.............................3 
   5. Security Considerations.........................................3 
   6. References......................................................3 
   AuthorÆs Address...................................................5 
    
  
Haberman, Thaler                                                     1 
 


 
Internet Draft   Unicast Prefix-based IPv6 Multicast      August 2000 
    
 
1. Introduction 
    
   This document specifies an extension to the multicast portion of the 
   IPv6 addressing architecture [RFC 2373].  The current architecture 
   does not contain any built-in support for dynamic address 
   allocation.  This proposal introduces encoded information in the 
   multicast address to allow for dynamic, unicast prefix-based 
   allocation of IPv6 multicast addresses, as well as allocation of 
   source-specific multicast addresses. 
    
 
2. Terminology 
    
   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]. 
    
    
3. Multicast Address Format 
    
   Section 2.7.2 of RFC 2373 defines the following operational format 
   of IPv6 multicast addresses: 
    
     |    8   |  4 |  4 |               80               |     32     | 
     +--------+----+----+--------------------------------+------------+ 
     |11111111|flgs|scop|     reserved must be zero      | group ID   | 
     +--------+----+----+--------------------------------+------------+ 
 
   This document introduces a new format that incorporates unicast 
   prefix information in the multicast address.  The following 
   illustrates the new format: 
    
    
     |   8    |  4 |  4 |   8    |    8   |       64       |    32    | 
     +--------+----+----+--------+--------+----------------+----------+ 
     |11111111|flgs|scop|reserved|  plen  | network prefix | group ID | 
     +--------+----+----+--------+--------+----------------+----------+ 
    
 
                                   +-+-+-+-+ 
   flgs is a set of 4 flags:       |0|0|P|T| 
                                   +-+-+-+-+ 
    
           o P = 0 indicates a multicast address that is not assigned 
              based on the network prefix. 
           o P = 1 indicates a multicast address that is assigned 
              based on the network prefix. 
           o If P = 1, T MUST be set to 1, otherwise the setting of 
              the T bit is defined in Section 2.7 of RFC 2373. 
    
   The reserved field MUST be zero. 
  
Haberman, Thaler                                                     2 
    


 
Internet Draft   Unicast Prefix-based IPv6 Multicast      August 2000 
    
    
   plen indicates the actual number of bits in the network prefix field 
   that identify the subnet when P = 1. 
    
   network prefix identifies the network prefix of the unicast subnet 
   owning the multicast address.  If P = 1, this field contains the 
   unicast network prefix defined in [RFC 2374] and assigned to the 
   domain owning, or allocating, the multicast address. 
    
   With the network prefix-based architecture and the current unicast 
   address architecture [RFC 2374], the network prefix portion of the 
   multicast address will be at most 64 bits. 
    
   The scope of the unicast-prefix based multicast address MUST NOT 
   exceed the scope of the unicast prefix embedded in the multicast 
   address. 
    
   The lifetime of a unicast prefix-based multicast addresses MUST be 
   less than or equal to the Valid Lifetime field in the Prefix 
   Information option, corresponding to the unicast prefix being used, 
   contained in the Neighbor Discovery Router Advertisement message 
   [RFC 2461]. 
 
    
4. Source-Specific Multicast Addresses 
    
   The unicast prefix-based IPv6 multicast address format supports 
   Source-specific multicast addresses, as defined by [SSM ARCH].  To 
   accomplish is, a node MUST: 
    
           o Set P = 1. 
           o Set plen = 0. 
           o Set network prefix = 0. 
    
   These settings indicate that the multicast address is being used in 
   source-specific multicast transmission.  The source address field in 
   the IPv6 header identifies the owner of the multicast address. 
    
    
5. Security Considerations 
    
   Using unicast network-prefix based multicast addresses can sometimes 
   aid in identifying the allocation domain of a given multicast 
   address, although no guarantee is provided. 
    
   Using source-specific multicast addresses can sometimes aid in the 
   prevention of denial-of-service attacks by arbitrary sources, 
   although no guarantee is provided. 
 
 
6. References 
    
  
Haberman, Thaler                                                     3 
    


 
Internet Draft   Unicast Prefix-based IPv6 Multicast      August 2000 
    
   [RFC 2026] S. Bradner, "The Internet Standards Process -- 
              Revision 3", BCP 9, RFC 2026, October 1996. 
    
   [RFC 2460] S. Deering and R. Hinden, "Internet Protocol, Version 6 
              (IPv6) Specification", RFC 2460, December 1998. 
     
   [RFC 2373] R. Hinden and S. Deering, "IP Version 6 Addressing 
              Architecture", RFC 2373, July 1998. 
    
   [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate     
              Requirement Levels", RFC 2119, BCP14, March 1999. 
    
   [RFC 2374] R. Hinden, M. OÆDell, and S. Deering, "An IPv6 
              Aggregatable Global Unicast Address Format", RFC 2374, 
              July 1998. 
    
   [RFC 2461] Narten, T., Nordmark, E., Simpson, W., "Neighbor 
              Discovery for IP Version 6 (IPv6)", RFC 2461, December 
              1998. 
    
   [SSM ARCH] H. Holbrook and B. Cain, "Source-Specific Multicast 
              for IP", Work In Progress, March 2001. 

  
Haberman, Thaler                                                     4 
    



 
 
AuthorÆs Address 
    
   Brian Haberman 
   Nortel Networks 
   4309 Emperor Blvd. 
   Suite 200 
   Durham, NC  27703 
   1-919-992-4439 
   haberman@nortelnetworks.com 
    
   Dave Thaler 
   Microsoft Corporation 
   One Microsoft Way 
   Redmond, WA  48105-6399 
   1-425-703-8835 
   dthaler@microsoft.com 
    
    

  
Haberman, Thaler                                                     5