One document matched: draft-ietf-malloc-ipv6-guide-01.txt

Differences from draft-ietf-malloc-ipv6-guide-00.txt

   MALLOC Working Group                                         B. Haberman
   Internet Draft                                           Nortel Networks
   draft-ietf-malloc-ipv6-guide-01.txt 
   July 2000 
   Expires January 2001 
 
 
                     Dynamic Allocation Guidelines  
                      for 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 document specifies guidelines to be used when allocating IPv6 
   multicast addresses.  The purpose of these guidelines is to reduce 
   the probability of IPv6 multicast address collision, not only at the 
   IPv6 layer, but also at the MAC layer of media that utilizes IEEE 
   802 addressing.  
    
    
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 
    
   This document specifies guidelines to be used when allocating IPv6 
   multicast addresses.  The purpose of these guidelines is to reduce 

  
Haberman                                                             1 
 
 

Internet Draft    IPv6 Multicast Address Guidelines          July 2000 
    
   the probability of IPv6 multicast address collision, not only at the 
   IPv6 layer, but also at the MAC layer of media that utilizes IEEE 
   802 addressing. 
    
   With the current IPv6 multicast address architecture [RFC 2373] and 
   the proposed extension to that architecture specified in [NEW ARCH], 
   a set of guidelines is needed for multicast address allocation 
   servers [MALLOC] to use in assigning IPv6 multicast addresses. 
    
   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 multicast address.  By supporting several mechanisms, these 
   guidelines can accommodate the varying capabilities of multicast 
   address allocation servers. 
 
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 IDs 
   less than or equal to 32 bits long will generate unique MAC 
   addresses within a given multicast scope.   
    
   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 mechanisms 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 initialized according to [RFC 2373] and 
   [NEW ARCH]. 
    
   The T flag of each dynamically allocated multicast address MUST be 
   set to '1'.  Permanent addresses MUST NOT be allocated using the 
   multicast address allocation architecture. 
    
   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 include using an MD5 message-digest [RFC 1321] or portions of 
   an NTP [RFC 1305] timestamp. 
    
   The high-order bit of the Group ID MUST be set to '1'.  This will 
   distinguish the dynamically allocated addresses from the permanently 


  
Haberman                                                             2 
    
 

Internet Draft    IPv6 Multicast Address Guidelines          July 2000 
    
   assigned multicast addresses defined in [RFC 2375] at the MAC layer 
   on any media that utilizes IEEE 802 addressing. 
    
   A request for multiple multicast addresses 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. Multicast Address Lifetime 
    
   The lifetime of the assignment of unicast prefix-based multicast 
   addresses MUST be less than or equal to the Valid Lifetime field in 
   the Prefix Information option contained in the Neighbor Discovery 
   Router Advertisement message [RFC 2461]. 
    
    
6. Security Considerations 
    
   This document does not have any known impact on Internet 
   infrastructure security. 
    
    
7. Acknowledgements 
    
   The author would like to thank Dave Thaler and Steve Deering for 
   their thorough review of this document. 
    
 
8. References 

    
   [RFC 2026] Bradner, S., "The Internet Standards Process -- Revision 
              3", BCP 9, RFC 2026, October 1996. 
    
   [NEW ARCH] Haberman, B., Thaler, D., "Unicast Prefix-based IPv6 
              Multicast Addresses", Work in Progress, July 2000. 
    
   [RFC 2373] Hinden, R., Deering, S., "IP Version 6 Addressing 
              Architecture", RFC 2373, July 1998. 
    
   [MALLOC]   Thaler, D., Handley, M., and Estrin, D., "The Internet 
              Multicast Address Allocation Architecture", 
              draft-ietf-malloc-arch-04.txt, January 2000. 
    
   [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate     
              Requirement Levels", RFC 2119, BCP14, March 1999. 
    
   [RFC 2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet 
              Networks", RFC 2464, December 1998. 
  
Haberman                                                             3 
    
 

Internet Draft    IPv6 Multicast Address Guidelines          July 2000 
    
    
   [RFC 1305] Mills, D., "Network Time Protocol (Version 3) 
              Specification, Implementation", RFC 1305, March 1992. 
    
   [RFC 1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, 
              April 1992. 
    
   [RFC 1750] Eastlake, D., Crocker, S., Schiller, J., "Randomness 
              Recommendations for Security", RFC 1750, December 1994. 
    
   [RFC 2375] Hinden, R., Deering, S., "IPv6 Multicast Address 
              Assignments", RFC 2375, July 1998. 
    
   [RFC 2461] Narten, T., Nordmark, E., Simpson, W., "Neighbor 
              Discovery for IP Version 6 (IPv6)", RFC 2461, December 
              1998.




































  
Haberman                                                             4 
    


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











































  
Haberman                                                             5