Internet DRAFT - draft-haberman-malloc-ipv6-prefix

draft-haberman-malloc-ipv6-prefix





        MALLOC Working Group                                         B. Haberman
        Internet Draft                                           Nortel Networks
        draft-haberman-malloc-ipv6-prefix-01.txt 
        March 2000 
        Expires September 2000 
      
      
                          Dynamic Allocation Guidelines for 
                    Network 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 
         
        With the current multicast address architecture and the proposed 
        multicast address architecture, a set of guidelines is needed for 
        multicast address allocation servers to use in assigning IPv6 multicast 
        addresses.  The purpose of these rules is to reduce the possibility of 
        address collision not only at layer 3, but also on devices at layer 2.  
         
         
     1. 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]. 
         
         
     2. Introduction 
         
        With the current multicast address architecture [RFC 2373] and the 
        multicast address architecture proposed in [NEW ARCH], a set of 
        guidelines is needed for multicast address allocation servers [MALLOC] 
        to use in assigning IPv6 multicast addresses.  The purpose of these 
        rules is to reduce the possibility of address collision not only at 
        layer 3, but also on devices at layer 2. 
         
        These guidelines specify how the lowest 32 bits of the IPv6 multicast 
        address are chosen and assigned.  The guidelines specify several 
        mechanisms that can be used to determine the lowest 32 bits of the 

       
     Haberman                                                             1 
      
      

     Internet Draft   IPv6 Multicast Address Architecture        March 2000 
         
        multicast address.  By having several mechanisms of varying complexity, 
        implementers and operators have the flexibility to choose a mechanism 
        that is appropriate for their application. 
      
     3. Assignment of New IPv6 Multicast Addresses 
         
        The current approach [RFC 2464] to map IPv6 multicast addresses into 
        IEEE 802 MAC addresses takes the low order 32 bits of the IPv6 
        multicast address and uses it to create a MAC address.  Group ID's less 
        than or equal to 32 bits long will generate unique MAC addresses.   
         
        The goal of this document is to present several mechanisms implementers 
        and operators can use to select the group ID portion of the address so 
        that the possibility of collisions at the IP layer and at the IEEE 802 
        layer is reduced.  The following section presents several different 
        mechanism of varying complexity that can be used to select an 
        appropriate group ID. 
         
         
     4. Group ID Selection Guidelines 
         
        The following guidelines assume that the upper 96 bits of the IPv6 
        multicast address have been set up.  For unicast network prefix-based 
        multicast addresses, the set up of those bits is done in the following 
        manner: 
         
                o  An IPv6 multicast address prefix is initialized with the 
                   appropriate flags and scope fields 
                o  The IPv6 Network Prefix is inserted into the address and the 
                   plen field is set.  The Network Prefix is obtained from the 
                   periodic Router Advertisements. 
                o  The reserved field in the IPv6 multicast address is set to 
                   zero 
         
        With the multicast address architecture in [RFC 2373], the set up of 
        those bits is done in the following manner: 
         
                o  An IPv6 multicast address prefix is initialized with the 
                   appropriate flags and scope fields 
                o  The reserved field in the IPv6 multicast address is set to 
                   zero 
         
        The group ID portion of the address is set using either a pseudo-random 
        32-bit number or a 32-bit number created using the guidelines in [RFC 
        1750].  Possible approaches to creating a pseudo-random number are to 
        use an MD5 message-digest [RFC 1321] or portions of an NTP [RFC 1305] 
        timestamp. 
         
        Requests for more than one multicast address SHOULD be handled 
        atomically.  One possible approach is to use the initial group ID, 
        created using the guidelines above, as the base address in a contiguous 
        block of multicast addresses.  Another approach is to create multiple 
        group IDs and generate the appropriate multicast addresses. 
         
         
     5. Security Considerations 
         
        This document does not have any direct impact on Internet 
        infrastructure security. 

       
     Haberman                                                             2 
         
      

     Internet Draft   IPv6 Multicast Address Architecture        March 2000 
         
         
      
     6. References 
         
        [RFC 2026] S. Bradner, "The Internet Standards Process -- Revision 3", 
                   BCP 9, RFC 2026, October 1996. 
         
        [NEW ARCH] B. Haberman, "IP Version 6 Multicast Addressing 
                   Architecture", draft haberman
                                       -        -ipngwg-mcast-arch-00.txt, 
                   December 1999. 
         
        [RFC 2373] R. Hinden, S. Deering, "IP Version 6 Addressing 
                   Architecture", RFC 2373, July 1998. 
         
        [MALLOC]   D. Thaler, M. Handley, and D. Estrin, "The Internet 
                   Multicast Address Allocation Architecture", 
                   draft-ietf-malloc-arch-04.txt, January 2000. 
         
        [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate     
                   Requirement Levels", RFC 2119, BCP14, March 1999. 
         
        [RFC 2464] M. Crawford, "Transmission of IPv6 Packets over Ethernet 
                   Networks", RFC 2464, December 1998. 
         
        [RFC 1305] D. Mills, "Network Time Protocol (Version 3) Specification, 
                   Implementation", RFC 1305, March 1992. 
         
        [RFC 1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321, 
                   April 1992. 
         
        [RFC 1750] D. Eastlake, S. Crocker, J. Schiller, "Randomness 
                   Recommendations for Security", RFC 1750, December 1994. 




























       
     Haberman                                                             3 
         



      
     Author's Address 
         
        Brian Haberman 
        Nortel Networks 
        4309 Emperor Blvd. 
        Suite 200 
        Durham, NC  27703 
        1-919-992-4439 
        Email : haberman@nortelnetworks.com 


















































       
     Haberman                                                             4